Product: AT5000 power amp
Manufacturer: Astin Trew - UK
Cost: £800 YMMV
Product: Usher R1.5 power amp
Manufacturer: Usher - Taiwan
Importer: HIAudio - UK
Cost: £1550 YMMV
Product: Belles Soloist 5 power amp
Manufacturer: Power Modules - USA
Importer: Coherent Systems - UK
Cost: £1100 YMMV
Reviewer: Maarten van Casteren - TNT UK
Reviewed: February, 2010

Introduction

I have been looking for a really good power amp for a while now. I found my Django preamp years ago, and still like it very much, but I haven't been as successful in finding a partnering power amp. My trusty old Electrocompaniet ECI-2 still works, but it's actually an integrated amp and also getting a bit old. I've reviewed several amps that sounded slightly better, mostly more punchy and cleaner, but none that tempted me into buying. The only exception was the wonderful Vincent SP-331MK amp, and I still regret letting that one go.

After my visit to the National Audio Show in September I decided to have a last stab at finding the right power amp for my system and I requested three amps for review that all seemed excellent candidates in their own way. These were the Belles Soloist 5, the Astin Trew At5000 and the Usher Reference 1.5. I'll introduce them first before we go into the 'Sound' section for the really interesting stuff.

All three amps were used with my Dynaudio Contour 1.8 mk2 speakers, my Django transformer preamp and my Astin Trew At3500plus CD player. My Vintage Micro Seiki DQX-500 turntable, with Denon DL160 cartridge and Cambridge Audio 640p phono stage was used as an alternative source as well. All amps were used for an extensive period on their own, but also compared directly to the other two amps on several occasions.

The Belles Soloist 5

At the NAS I noticed the Belles Soloist 3 and 5 pre and power combination. They simply looked very cute, and they were affordable too, compared to the other amps from Belles, that is. Tony Sallis, MD of Coherent systems who import Belles in the UK, was there and told me that I would be surprised by them, but he would say that wouldn't he? Nevertheless, I was intrigued and asked if I could review them. The opportunity to try a set of real Belles amps in my system was just too tempting.

When they arrived I was very pleasantly surprised indeed, by their size to begin with. The boxes they arrived in were just impossibly small, and the amps contained in them were even smaller than I remembered from the show. You can quite easily pick up the power amp with one hand! I cannot say how much of a relief this is, after I've had several enormous amps in my system in the months before. These are so easy to accommodate, and they take up so little space that you cannot help but appreciate them. Why do all these other amps have to be so big and heavy if it is clearly possible to make things much smaller and more practical? And if you want things to be even more compact and practical then you'll be delighted to know that Belles have also just introduced an integrated version of the Soloist amps.

Build quality is really excellent. And in spite of their small size these units feel very well put together. Especially the power amp makes a really solid impression. Case work and connectors are all of very good quality and the amps both look very purposeful and serious, in a minimalist way. The preamp turned out to have a technical problem, so the power amp was only used with my Django, like the other two. The power amp only took a few hours to come on song, and takes about an hour to reach full potential again after having been switched off. The design is solid state class A/B and delivers 65 watts into 8 ohms and 110 into 4 ohm. It always stays very cool, even when pressed hard.

The Astin Trew At5000

I reviewed the wonderful Astin Trew At2000plus integrated amp some time ago, but I liked it most used as a power amp with my Django preamp. Michael Osborn then told me that if I liked the At2000plus like that, I would love the At5000, because it is basically the same power amp section as used in the At2000plus, but with a bigger, dual mono power supply. It also is simpler, obviously, with less stuff in the case to interfere. So, it should be even better, and here I am, trying out an At5000.

It certainly looks good and is very nicely build, as is all Astin Trew stuff, and feels substantial enough. The inside looks great too, with two large toroid transformers, excellent component quality and neatly organised circuit boards. The whole amp is completely dual mono and a lot of attention has been given to the power supply. For a start, it is generously dimensioned for an amp of this power rating, with oversized transformers and reservoir capacitors. Astin Trew also use very quiet Schottky diodes and smaller values of high quality, audiophile polypropylene capacitors in parallel with the normal electrolytes. The output stage uses a single pair of MOSFET device per channel. The valve, with damper, is actually part of the power supply and not in the signal path at all.

Rated output power is 50 watts in 8 ohm and 100 watts in 4 ohm, making it the least powerful amp of the three. It was primarily designed to drive smaller stand mounted speakers of high quality. Astin Trew recommend bi-amping two At5000 amps for optimum results with floor standing speakers, but my Dynaudio speakers don't allow this so I wasn't able to try this out. A pair of At5000's did sound very good driving Revolver speakers at the NAS, though, so I'm sure this is a very useful option.

The Usher Reference 1.5

This amp is a real monster! It weighs 40 kilos and is enormous. The big handles at the front and the back are not there just for show, you really need them! It delivers 2 times 150 watts into 8 ohms and up to 500 into loads as low as 1 ohm, for a single channel! The amp is clearly heavily biased into class A, although there's no specification telling me how many real class A watts it actually produces. The output stage uses 8 pairs of transistors in parallel for each channel and the heat sinks are gigantic. I have to admit that I have had an eye on this amp for a while now. It seems to be this biggest amp that I could possible afford, and probably with the highest amount of class A watts too. Very impressive.

Build quality is epic. The loudspeaker terminals are the best I've ever seen, even if there's only a single pair. I don't like bi-wiring anyway. Everything is bombproof and massively over designed. The mains transformer is gigantic and the output transistors are mounted on a slab of copper that is about 2 cm thick! It simply shouts 'expensive muscle amp' at you. Given all of that, the asking price is actually not very high, but still the most expensive of the three, and double the price of the Astin Trew.

This amp looks very much like the Threshold amps that were available years ago, both cosmetically as well as in specifications. Some people claim it is a copy, others say Usher bought the design, but the truth seems to be that it is a design inspired by the Threshold, with some modifications. There is a smaller version, the R1.3, and some versions that are even more powerful, but the R1.5 seems to be the only one that is available in the UK.

Power consumption is a problem with this monster. It already uses about 55 Watt when still switched off! Yes, indeed, it probably uses more power when not even on than most other power amps playing music! Part of the circuitry is always switched on, it seems, even if the main switch at the front is off. Switching the whole amp on raises the power consumption to about 260 watt, which is what you would expect from an amp like this. Now, 1 watt of continuous consumption over a whole year will cost you about £1 in the UK. So, just having this amp connected to the mains, and not ever switching it on, will already cost you £55 a year. Switch it on for an average of 4 hours a day and you are looking at close to £100 each year on electricity. This means that over an expected life of about 15 years, this amp will cost about as much on electricity as on the purchase! The only way to avoid this is to switch the socket off, or unplug it, when not in use. But it takes a while to warm up, certainly if it has been unplugged, so this is slightly unpractical. It could be argued that buying a 'normal' amp that costs about a £1000 more than this one would cost you less in the long run, and could be more practical to live with, or even sound better. In other words, this Usher will have to sound very good indeed to earn its keep.

For brave, and rich, audiophiles this amp can even be bridged, turning it into a very powerful mono block. I obviously couldn't try that, but I also think this would be complete overkill, at least in my room. Also, when your power amps weigh more than you yourself, I think you've crossed a line.

The Sound

Here we go. The bit that really counts. Which one sounds best? Well, if you want me to select a winner you will be disappointed. It is not that I don't want, or don't dare, to tell you which one is best, but the fact of the matter is that these amps are quite different. Each amp has its own qualities and each one is distinctly different to the other two. I can also imagine each amp working very well in certain systems and with certain music. Which one is best will depend on what you want from an amp. I did end up with a preference, but it was for the most expensive one. It is no surprise that an amp costing twice the money is likely to sound better.

I also have to stress that these amps all sounded great to me when I tried them separately. I was more than impressed with each one of them, and only really found out the strong and weak points when I started to compare them directly. I was really surprised to find how one amp could expose weaknesses, or strengths, in another one when you switch directly from one to the other. Things that I wouldn't have noticed in isolation became quite clear in comparisons. For that reason this review has been a bit of an eye opener to me.

The Belles

Let's start with the Belles. It was the first one to arrive, so it is only fair to report on its sound first. There is the temptation to see this amp as a 'baby-Belles' and to not take it completely serious because of its size. And it has to be said that the next power amp from Belles is more than three times the price. Can this really sound like a proper Belles? The answer is yes. I was completely convinced by it within minutes. This is no toy amp, no little starter model or second-system amplifier. This is a serious amp. The most unexpected thing is the bass. This little amp really knows how to do bass! Deep, controlled, full bodied and tuneful, it made my foot tap. Bigger amps can produce even tighter and deeper bass, but for the price this is really very good.

The sound stage is also excellent. More deep than wide, but natural in its proportions, well focussed and nicely layered. The tight and deep bass makes for stable and convincing images. This amp is able to produce rock-solid center images, with singers taking on a real physical presence. Closely miked voices can be very intimate because of that. It also has the ability to throw an image in front of the speakers, which can work extremely well with some recordings. Of course, this also means it can sound a little bit 'forward', which can be less pleasant with other recordings.

The balance is neutral, with enough weight and warmth down below and enough sparkle at the top end. The sound is lively and engaging, with good dynamics and not even a hint of softness. The downside of this is that there are more refined amps at the price. But energy and refinement are very much tradeoffs at this price level, and the Belles power amp is an excellent performer overall, losing only a tiny bit of smoothness in return for a lot of fun.

When pushed to play louder the sound does have a tendency to harden up a bit. So if you like to play very loud you will need to combine this amp with above average sensitive speakers, unless you have a small room. There's no need to go out and buy horn speakers, though, as for most circumstances the Belles has more than enough power. It certainly was powerful enough for me.

The Usher

The next amp was the Usher. The thing that immediately draws the attention when you start listening to this amp is the bass. It is strong, deep, warm, tight and very tuneful. It is the best bass I've ever heard coming from my Dynaudio Contour 1.8 mk2 speakers. I actually didn't know they could do bass like that! The woofers are controlled completely, reducing boom, while the added slam in the bass is impressive. This is not ‘dry control', this is really kicking some life into the bottom octave, adding both extension and texture. The result is rock solid, fruity and propulsive bass that underpins the music in a very convincing way.

The next thing that becomes very clear soon after you've recovered from the shock of hearing that bottom end is the dynamic range. This amp will go loud, and sound effortless at almost any level. You can basically turn the volume up as far as you want, and the Usher will just keep playing music. Everything will just get bigger, and bigger, and bigger. In my room, and with my speakers, the limit is usually the bass which becomes a bit too strong at some point. The combination of high volume, effortless dynamics and great bass is very satisfying. And it works with all kinds of music and all sorts of recordings, as it doesn't really depend on resolution. It's not that this amp doesn't have adequate resolution or isn't revealing, it's just that it doesn't rely on these properties to make an impression. It's an iron fist in a velvety glove, and that works well with most recordings. Bad recordings sound bearable, better recordings sound good and the best recordings simply sound amazing.

I just said 'velvety' glove as the top end is actually not as good as the bottom end. A sweet, silky and spacious treble would be the ideal complement for the warm and powerful bass, but in reality the top end is not in the same class as the bottom end. It is not bad, not by a long way, but it can be a little bit sibilant on some recordings and a tiny bit edgy on others. This is not a big problem. You cannot expect a £1550 amp to be completely perfect in all respects. It is impressive enough as it is. But if the top end is your first priority then you might be able to find something better at the price. You'll have to pay a big price at the other end of the spectrum, though, as no other amp at this price has bass like this one, certainly not one that beats it in the treble. Expect to pay several times more for an amp that can do all of that. For me, if this is a compromise, it certainly is the best possible compromise that I could afford. Asking for more just feels greedy.

That just leaves the crucial midrange, which is excellent. It must partly be the influence of that great bass, but the mids are nice and warm, with great solidity and excellent transparency. The soundstage is wide and deep with good focus and excellent stability. Voices, especially female ones, can suffer slightly by the added sibilance of the top end, but are still reproduced well enough. Again, it is that low end underpinning that adds the weight to give a voice that little extra solidity and presence.

The Astin Trew

The last amp to arrive was the Astin Trew. The At5000 produces what could perhaps be called the Astin Trew house sound. Very smooth, nicely detailed and on the warm side, with a nice touch of richness to the midrange. It is fantastic with voices, producing a very natural, elegant and sweet sound that brings out the best in well recorded vocals. It is also slightly soft, especially compared to the Belles Soloist power amp, but it isn't as soft as the At2000plus integrated was. In this case it makes for a nice, relaxed sound, without the feeling you're missing out on anything. The soundstage is nicely proportioned and focus is excellent. The overall impression is of a very natural and unforced sound that can be listened to for hours without fatigue or boredom. It is especially good at lower level, late-night listening, showing plenty of detail and reproducing the music very effectively, without the need to turn the volume up.

One of the At5000's strengths is, like the At2000plus, its ability to step aside and let the music through without much interference. It simply doesn't draw a lot of attention to itself, which is a very good thing for an amp. It also shares the At2000plus' even-handedness and coherence. It can cope with all sorts of music, with the possible exception of hard rock, and always conveys the musical message, not the audiophile attributes.

When pushed a bit harder the amp started to struggle a bit. The bottom end became slightly softer, while the top end had a tendency to harden up ever so slightly. In combination this produced a shift to a sound that was a bit brighter overall. This can be a little bit frustrating if you want this amp to rock, and turn the volume up a bit. You do this to get a bit more impact and weight, but the amp responds by sounding a bit lighter instead. In comparison to the Usher this makes the At5000 a little bit of a lightweight. I do have to add that my Dynaudio speakers like a bit of power and have the tendency to suck the life out of an amp. In combination with more efficient speakers this amp will be absolutely lovely. Another solution, very much favoured by Michael Osborn, is to simply use two At5000's and go bi-amping. He did suggest this to me, but sadly this is not possible with my Dynaudios. The good news is that 2 At5000 amps will be about the same price as a single Usher R1.5, so this is actually a very realistic alternative. I just wish I could have tried it myself.

Even after this criticism I have to say that the At5000 is a very satisfying amplifier that doesn't really have any weak points, as long as you stay within its comfort zone. Spectacular audiophile tricks can seduce the listener in the short term, but this amp has the ability to really convince in the long run.

Comparisons

Clearly each one of these amps has their own strengths, and weaknesses. The Astin Trew is silky and refined, and the most affordable. It certainly represents the best value of the three amps here. But it can sound a tad soft and over-polite and will sound slightly thin when driven harder. It certainly is the softest amp here, something that becomes clear when you compare it to the Belles. When comparing to the Usher a certain lack of weight can be noted, even when the At5000 in isolation actually sounds fine in this respect.

The Belles is very lively and engaging, and has nice weight, but can sound a bit processed and edgy. You could just as well call it ‘crisp', I suppose, depending on the recording and your taste. When comparing it to the Astin Trew it made the acoustic image seem to be a bit artificial and ‘over-sharpened', to use a photographic metaphor. But it rocks much better than the At5000, which is simply a bit too soft to really kick things up a bit.

The Usher has great bass and massive power, but lacks a little bit of refinement in the top end. It can make sibilant recordings a bit unpleasant, from time to time. The Astin Trew beats it in the upper frequencies, but doesn't even come close in the lower half of the spectrum. The Usher also is the most expensive amp, and that is not even counting the cost of electricity.

If you want refinement the choice is easy: go for the Astin Trew. If you think it is too light-weight, buy another one and start bi-amping, if you can. If you like an amp that is lively and can 'rock', and hate 'polite' hifi then the Belles is your ticket. It really is an excellent all-round amp if you like a bit of energy. And if you want authority and a fantastic bottom end, with super control over your speakers, the Usher is your amp.

When I was comparing the Usher to the other amps I did prefer it but it took me a while to find out why. It is weightier and sounds bigger, but the other two are excellent amps too. Still, the Usher seemed to have that little bit extra that made me want to listen to it, and that made music more appealing. Then I remembered the first time I watched 'Star Trek, the Next Generation' while playing the sound through the stereo. If you do this you suddenly hear a constant hum in the background. It's the sound of the ship, and I couldn't hear this through my ordinary telly. It really adds to the overall feeling of the series. It gives you a stronger feeling of being there. You can feel the ship. The same thing happens with the Usher: it seems to bring out an undercurrent in some music that creates a stronger emotional response. You feel the space and acoustics better, and have a stronger sense of being in the same room as the musicians. It connects you to the music, and I have to admit that is addictive. Compared to all other amps I've had in my system this offers an almost tactile sensation, and perhaps that is why the emotional connection is easier to make. What ever it is, I like it, very much.

Conclusion

I did prefer the Usher in the end, but I cannot say that this automatically makes it the winner. It also is the most expensive of the three, and will cost you almost the same as the purchase price again in electricity if you don't unplug it when not in use. It also weighs 40 kilos and is very big. All of this almost disqualifies it, in my opinion, but I have to admit it was also the best sounding one of the three. Its bottom end is simply fantastic.

That doesn't make the other two bad sounding amps, of course. The Astin Trew is great if you like a smooth, silky and refined sound. It works great with live recordings and is fantastic with voices. Overall it probably is the most 'valve-like' of these three amps. For the price, this is an amazing amp, and in terms of refinement it is one of the best I've ever heard. If that's your cup of tea, the At5000 is an absolute bargain even, or maybe especially, if you get two of them and bi-amp.

The Belles is the opposite of the Astin Trew. Not especially sweet, but energetic, fast and exciting. This is the amp for you if you like a bit of spark and drive in your music. It has great bass too and will play loud enough for most situations. It is also easy to accommodate and very well built.

Finally, I have to confess something. I wanted to hate the Usher for being so big and heavy, and for wasting so much energy. But I ended up buying it. I just couldn't let it go. If that sounds like a recommendation, so be it. Just don't discard the other two amps. They deserve more than that.