Which amp matches best my JM Lab Mezzo Utopia ?

I have thought it is parallel single ended very much like the Aleph.

The way I understand it (I guess I have to say I am an electrical engineer), is that the Aleph is truly single-ended but the XA series is, as Pass puts it, "parallel single-ended" which to me is just marketing jargon to fool audiophools into thinking they have a single-ended output stage when in fact, the input is single-ended but differential. Parallel balanced output is not single-ended output. You have to read his website more carefully or just believe it and get an XA160 and be happy!

Arthur

The BAT solid state amps deliver lots of current, so that handles your load requirement, and are biased heavily into Class A. As such, they run hot, but I've owned BAT pre/power for the last seven years with no desire to make a change. Don't know them with the Utopias, but my Magneplanars are 4 ohms nominal, and there's never an issue of drive or control.

A friend of mine uses a LA audio 300B amp (mono amps 8 watt), it's a very fine combination. 3.8 Ohm isn't that low, if i remeber right they have a efficiency of 92 db, i think this is more important.

I read somewhere that it's not recommended to use SET amps with speakers that have impedance below 8 ohms.