I have found a pdf of the XA100.5 :
http://www.electori.co.jp/PASS/XA100.5.pdf
The 2 big differences are :
selectable gain : 26 or 30 db (the XA100 has only 26 db gain) and a much higher max current : 28 A against 5 A. This point should bring a better power with low impedance speakers.
The other specifications are very close.
The XA60.5 seems to be available too, but no XA160.5 or XA200.5.
http://www.electori.co.jp/PASS/XA100.5.pdf
The 2 big differences are :
selectable gain : 26 or 30 db (the XA100 has only 26 db gain) and a much higher max current : 28 A against 5 A. This point should bring a better power with low impedance speakers.
The other specifications are very close.
The XA60.5 seems to be available too, but no XA160.5 or XA200.5.