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