I thought I would post this here, just because I know Paul (above) and have the pre-amp from him that is on this thread. I've just come to the end of an extended period of using the matching ZL120 power amps and so thought i would share my experiences here.
Sometime around last November my much loved Silverware 833 mkII SET amps decided they were going to take a break from working. They’d been intermittently playing up, every now and then the right channel would drop playing music and instead emit a horrendous screeching noise that would cause me to shit my pants before I managed to hit the kill swtich! It was always temporary; turning everything off and leaving it a while would mean normal service was resumed. Then one day the right channel just gave up the ghost altogether. Swapping tubes, both the input and the output sets, from left to right made no difference so it was decided they needed to either go back to Leipzig where they were made, or else to a chap at Malvern who is a guru on all things SET. I really wanted them to go to the manufacturer because as well as the right amp giving up, the left had some legacy melting on the output tube Teflon mount from an early shorting when I first got them. This had somehow sorted itself out but was still something that shouldn’t really have happened.
It took seven months to arrange the return. Not entirely sure why, at least part of that was because I wasn’t pressing too hard (I knew my dealer was loath to send them back to Germany because that was a major headache with the shit show that is customs following Brexit) and the reason I wasn’t pressing too hard is because Paul very kindly loaned me the Concert Fidelity power amps that match the pre-amp I bought from him. I’ve had these amps now for seven months (Paul, really cannot thank you enough for this) and so I thought i would offer something like a review of them, purely for interest and perhaps because, being as these amps are available to buy, someone might be inclined to make Paul an offer on what would be a bargain of the century!
The the ZL-120s sit behind the true reference models, the ZL-200. They are solid state designs but they are MOSFET transistors, which I understand have a reputation for sounding ‘tube like’; I guess that means warmth and richness of timbre. They are capable of outputting 180 watts but they are also biassed to class A for the first 30 watts. I’ve tried these amps before with my Horns FP10s and had been hugely impressed by them. But with the much larger 15” bass driver Horns FP15s I now have, I’ve been blown away by them. The Horns are obviously an easy drive at 96db and nominal 8 ohm impedance, so the amps are, I think, never stretched beyond their 30 watt Class A bias, which I think is a big part of why they have sounded so good.
Obviously any design parameter in a hifi chain is about compromise; add more bass weight and leading edge drive and authority through a big meaty SS amp and compared to a flea powered high quality SET amp you might well trade that for transparency and, richness in timbre that many translate into the emotional engagement they have with music. It’s not until you get to stratospheric levels of quality and investment that you can start to expect both. I think the Heisenberg’s that our mutual friend has in his 'reference' system do that.
I also think these Concert Fidelity amps also get close. They do trade a little of the SET sweetness and transparency, but I also think that you could probably trade that back, say via a tube output DAC - I have 242 tubes in my Lampizator Golden Gate, so could withc to say a 45, splitting the difference between dark rich timbre of a 300B and the leading edge energy and drive of the 242 - or via the pre-amp, with a little more experimentation of the output tubes (though already the CV491 Hivacs I have are about as hens teeth rare, expensive and sweet as you can get with 12au7s).
These amps pack a meaty but rich punch. They have such a grip on my speakers; I’ve never heard bass so deep and well controlled in my front room. It’s solid and musical; a proper kick drum punch when required and deep and rich everywhere else. Yes there is quite a bit of it but it’s always well integrated with the rest of the music and never feels like it swamps the other registers.
The leading edge is exquisite as you would expect and hope. It is blade sharp, precise and super fast. Transients are so fast they sit in the Planck Time (aided by super light paper cones in bass mid drivers of the speakers and a horn loaded beryllium tweeter). With bebop/hardbop/postbop, where a transparent and liquid fluidity to match the playing of the maestros Davis, Parker, Coltrane, Monk, Blakey , Mingus et al, is always desired, the precision with which each note is played is ready compensation for the slight lack of liquidity that SS gives up to SET vacuum tube. And still the music positively rolls along, cresting and crashing like a wild surf, and with as much energy and vim. They are joyous.
I think retail they were positioned about £18,000 (UK) so to some extent they should be all kinds of wonderful and yet so many hifi components over deliver in one area (usually the ones that test and measure well), and fail miserably in others (the ones where you sit and listen and enjoy). These ZL-120s deliver across both. I’m not sure how much Paul wants for them but if the figure he’s tentatively suggested to me is right they would be the bargain of the century. I am very tempted to see how much money I could liberate from the 833s; if it were a net zero cost to exchange I would be very tempted indeed!