To Garrett Hongo,
I am wondering if you think the deHavilland KE50As would be a good match with the Quad ESL-63 speakers. The speaker's sensitivity is about 86dB. Would the VAC Phi 200 be a better choice for the Quads? Do you have any experience with the Quicksilver Silver 88 mono amps, which the manufacturer says work well with low-impedance speakers? Thanks for your time and insights.
Nice to hear from you. I've no direct experience with Quad ESL-63s myself, but I've heard from Kara Chaffee, chief engineer of deHavilland Electronics, that she has a client who drives Quad 988s, a 63-derived Quad, with deHavilland KE50As with very good results. The KE50As output 40W-45W and have a unique feature in an interstage transformer (in addition to the main power and output transformers) that maintains output at peak current levels. I just love their sound myself and am completely happy with them in my system with speakers different from yours.
Regarding the VAC Phi 200, I reviewed it too. The Phi 200 differs from the KE50A not only in output power (twice that of the KE50A), but also in character of sound. I'd say that, in my system, the Phi 200 is very resolving, sparkles, and is punchy in the bass, whereas the KE50A is very finely balanced through the frequency range. The Phi 200 is leaner sounding, whereas the KE50A is richer in the midrange. Not to say that one is "better" than the other, but that their spectral balances differ. The shorthand tekkie answer is that, though they both use the KT88 output tube, the Phi 200 is more toward the ultralinear style of sound, whereas the KE50A is with the triode sound. I use them both.
As for Quicksilver 88 mono amps, I do have some acquaintance with them, as I've a good friend in town who owns them and drives Cary Silver Oak speakers (88dB/6 ohms) with them. I do like their sound quite a bit and find them reliable with moderate-impedance speakers, but I can't say I'm confident how they'd work with speakers of low impedance. You'd have to take the manufacturer's word on that. I like Quicksilver a lot, but it's not in the same league as VAC or deHavilland. The sound is good but the build quality isn't the same, nor the reliability. That matters if you run equipment a lot, as I do. If you don't, then it's not as much a factor. I'd say Quicksilver is a value product and has a long-standing and solid reputation, whereas VAC and deHavilland are true high-end components. Let me know what happens! . . . Garrett Hongo