This new amp (like the original) is based on an amp I originally designed many years ago, of which hundreds were built. Most were operated as small PA or instrument amps, but many also found their way into home hi-fi systems. The amp is perfectly capable of driving 4 Ohms, provided the supply voltage is maintained at no more than ±35V.
This amplifier, although very simple, is capable of superb performance. This is not an amp to be under estimated, as the sonics are very good indeed, and this is due (in part, at least) to the inherent simplicity of the design. The amp is exceptionally quiet, and is reasonably tolerant of difficult loads. It is an ideal amplifier for biamped systems, and may be operated in bridge mode (BTL) if you use the recommended output transistors (which have the necessary power ratings).
The design has had the benefit of many, many years of consistent use, and this version is the best of all - the refinements ensure minimum "switch on" or "switch off" noise, and the availability of really good output devices has improved on a known and very stable design.
I have heard nothing but praise from those who have built this amplifier - the only feedback I have received has been very positive indeed. The sound quality is up there with the very best.