To Hans Wetzel,
I'm very impressed by the Luxman L-550AX driving my Quad ESL-63s (sensitivity of 86dB). Before I purchased it, I tried Hegel Music Systems' H80 integrated amp-DAC, then the Luxman L-505uX (returned because hum noise has been heard in headphone section). I have also driven the Quads by the Adcom GFA-535, B&K ST-202, and even the Crown K1 and K2 amps.
I agree with [your L-550AX] review, this is the best integrated amp under $5000. So far I was unable to test the Luxman's phono section -- my Denon DP-67L turntable is still in for service. The headphone section is as impressive as [the] amp itself. And not to forget, before I pulled the trigger for Luxman's L-550AX, I asked a dealer in Toronto if the Hegel H300 would be the better choice for ESL-63 speakers. But he chose the L-550AX over the Hegel H300. Now I'm wondering how [Luxman's larger] L-590AX (30Wpc) will sound at almost double the price of L-550AX. MusicDirect has a 60-day Satisfaction Guarantee. This is the place where I purchased the L-550AX.
That's a tough one, Adam. I agree with your dealer that, in terms of pure sound quality, the Luxman sounds better than the Hegel. That's not a knock against the H300. After all, I do own one, adore it, and appreciate the fact that it can do a lot more than the Luxman for roughly the same price. If you love what the Luxman does with your Quads, however, I don't think the Hegel is really an option for you.
So that leaves the more powerful and twice-as-expensive L-590AX. Remember that a doubling in amplifier power -- say, from 20Wpc to 40Wpc -- only produces an extra 3dB of output. In this case, the potential jump from 20Wpc to 30Wpc will only yield you 1.5dB of additional headroom. If you feel that the L-550AX is straining to really drive your Quads, then maybe that's worth it to you. But if you're satisfied with the sound you're getting from your current setup, I would not worry about spending nearly $9500 to maybe do a little bit better. You have one heck of an amp as it is! . . . Hans Wetzel