[PHC1]

Originally Posted by joeinid

SIDEBAR: Robert Harley on the Pass Labs XA100.5
The XA160.5 reviewed here is a scaled up version of the XA100.5 I reviewed in Issue 185. The XA160.5 employs the same low-level circuits and output-stage topology as the XA100.5, but adds more output devices and a larger power supply for 160W of output compared with the XA100.5’s 100W.

The XA100.5 is, in my view, one of the world’s great amplifiers. It is distinguished, primarily, by a tube-like liquidity in the midrange. It’s not that the XA100.5 has tube-like distortions, but rather that it lacks the characteristic signature of other solid-state amplifiers I’ve heard. Specifically, the XA100.5 has richly saturated tone colors, a wonderful warmth and body of timbre, and a completely grain-free rendering of instrumental textures. Moreover, it achieves these qualities without being colored, overly ripe, or falsely romantic. Rather than being tailored to sound pleasant, the XA100.5 simply imposes less of itself on the music than other solid-state amplifiers I’ve heard.

In addition, the XA100.5 is a powerhouse, at least when driving speakers of appropriate sensitivity for its output rating. It has iron-fisted control over the bottom end, super-fast reproduction of transient leading edges without the slightest bit of etch, and a sense of ease on even the most demanding dynamic contrasts.

But what really sets the XA100.5 apart is its supremely seductive midrange—lush without sounding syrupy, warm without sounding bloated, and richly refined and detailed without sounding analytical. This is an immensely involving set of qualities, and ones that make the XA100.5 easy to enjoy for extended listening sessions. –Robert Harley

Many class A amps seem to share some of those traits, mainly the liquid, rich and grain free presentation but not necessarily sounding anything less than resolving and very natural. I have not really heard a Class A amp that I did not really like or at least enjoy.