Best Amp for Timbre, Depth and Spatial Resolution?

If you plan to keep the B&Ws, the Ayre is likely one of the better choices. This speaker does not play well with tubes due to the nature of its load (4 ohms in the bass, 8 ohms in the mids and highs). Four ohm loads should be avoided with tube amps even if they have a 4 ohm tap- almost any output transformer will loose a good octave of bandwidth off of the bottom end, simply by going for 8 to 4 ohms and the distortion is usually higher.

If you really want serve your amplifier investment dollar, the speaker should be either 8 or 16 ohms for best results! Even if you have a transistor amp, if sound **quality** is your goal, you will do better with a higher impedance speaker as the amp will make less distortion (read: smoother, more transparent). If sound pressure is your goal, there is a slight advantage to four ohm speakers, assuming the efficiency is otherwise the same.

Unsound, if you would like I can show you a letter from Steve McCormick that disputes your position. It was written to Paul Speltz, who is known for the ZERO autoformer and the Anti-cables.

The letter states that with the DNA-series amplifiers they sound better driving a 4 ohm load through the ZEROs as opposed to direct), wherein the amp is loaded at 16 ohms, despite the fact that the amp has no trouble whatsoever doubling power into 4 ohms and can drive that load all day.

I also have spec sheets on a good number of solid state amps. Take a look- you will see that the 4 ohm distortion level is always higher than 8 or 16 ohms. This distortion is composed of a variety of harmonics, including the 5th, 7th and 9th, which contribute brightness and harshness. Take those things away, or reduce them and the system is instantly more musical.