I had (still have in reserve) an Aleph 5 that I used primarily with an Aleph P (remote version), but tried other combinations as well. In summary, stick to balanced, and go with an Aleph P (good luck finding one since they are being vaccumed up into the Far East market), or an X-1 or X-2. Single-ended tubed preamps come off sounding too dark and opague. THe Pass preamps seem to get the most from the A-5's modest power output. What you really need is a pair of good speakers and then start building around those.
I had a pair of the Talon Raven C speakers that were magical with the Aleph P/Aleph 5 combo. I'm still sorry I let that combination slip away; but I did because I had an anxious buyer for my Aleph P (check already in hand)that I was selling because I thought it to be the culpit producing some upper midrange hardness. Turned out it was the speakers needing further break in. Once they snapped in it was glorious for the 10 days I had that combination singing in unison. I was unable to locate an Aleph P to replace it, so I upgraded to the X-1, traded the Raven C up to the Firebirds, and bought a Pass X350 to drive them. All sounds very clean, very powerful, very spacious, but it somehow still doesn't have the magic I heard during those 10 days with the old combo. It just sounded supremely musical. Keep your Aleph 5. You should be able to buy a pair of Raven C's for about $4500-5000. Try calling the factory direct if you don't have a local dealer...ask for Mike.