One of the problems in reviewing some types of equipment is that what matters about its performance is almost as much its reliability as its more obvious sound qualities.

That's very true of power amps generally which tend to live tucked-away in studios or in racks beside P.A. mixers, given little thought unless they suddenly let you down. Way back in issue 5, we first tested the MOS-FET transistorised V500 Power Amp from H.H. It had already established a significant reputation for itself among many studio engineers for both its reliability and its excellent sound qualities, and we found, during the course of that first review, that (at least as far as sound went) the H.H. was a truly excellent quality piece of gear. But what about its reliability? Would it stand-up to the sort of hard use that a power amp must be able to endure to be worth buying?

H.H. (very kindly) have left the amp with us since that issue was published, during which time we have used it constantly for monitoring tests on speakers, general day to day Hi-Fi use, driving high power bass stacks and even on the road as a P.A. amp.

To date only one fault has manifested on our sample, a failure of the mains switch (a push button type). For no obvious reason this failed to lock in and was returned to H.H. for a repair. In a short while the amp was returned to us working normally, but we were unable to find out quite what the cause of this malfunction had been. Since then, however, the H.H. has performed without a problem.

In some ways, apart from talking about its reliability and its sound, there's not really a great deal to say about any power amp. Certainly, our original feelings as expressed in the initial review we ran have remained the same — perhaps the best we can do is quote them, "Transient attack (i.e. notes such as those from bass drums where the amp is called to move from low to high outputs very fast indeed) was as rapid and as uncoloured as anything I've ever heard and there was no discernable distortion caused by this rapid 'rise time' whatsoever".

"TRANSIENT ATTACK WAS AS RAPID AND UNCOLOURED AS ANYTHING..."

Initially we did complain to a very mild degree about a noticeable hum from the toroidal mains transformer fitted to our sample. In actual practice this was less of a trouble than it might have seemed at the time, even in quiet studio environments. We did, however, eventually get the fan working on the V500; something which we'd never achieved in our initial tests (it cuts in when a temperature of 63°C is reached in the V-Fet power transistors). Regrettably it was then that we discovered that the fan on our model had, probably, been jolted out of alignment when the unit had been initially shipped to us - at least we hope that was the cause — as it ran rather noisily and that would have proved obtrusive in a studio. Still, it would seem as if this could be considered a one-off fault and not worth counting against the amp as a type.

"NEVER ONCE DID WE FEEL THAT THERE WAS ANY DANGER OF DISTORTION COMING FROM THE AMP (EVEN WHEN DRIVEN RIGHT TO THE LIMITS)..."

By any standards the H.H. was impressive and it is with great reluctance that we will be returning it to its makers in the very near future. Despite the one failure (which we do not consider a significant problem) it performed unflaggingly on every test that we gave it and always came through sounding like the best Power amp we've come across. Further, we've had ample opportunities now to pit the H.H. against several other manufacturers' similarly rated power amps and have to say that we have consistently preferred the exceptional clarity and distortion-free performance from the V500. Never once did we feel that there was any danger of distortion coming from the amp (even when driven right to the limits) as the presence of LEDs indicating peak levels meant that we were always aware of when to stop hitting the loud pedal and screaming 'more! more!'

"...YOU WILL BE MOST UNLIKELY TO BETTER THIS AMP."

Overall we would suggest that the H.H. V500 is possibly the best sounding power amp that we have yet found, that its reliability seems to be satisfactory and that it would be the ideal purchase for anyone building a high quality studio monitoring system, ultra luxury Hi-Fi rig or P.A. system.

There are many power amps delivering the sort of rated output power that this H.H. can manage (250 watts per channel into 4 ohms) and some of them can be had for rather less money than is asked for by this maker — but, as with all things in life, you tend to get what you pay for. The sound quality from this amp and the constructional strength means that you are getting about the best that there is. In any application where quality performance is called for that means you will be most unlikely to be able to better this amp. We wish, quite honestly, that we could afford to keep it!

(RRP £573-97)