Driving MBL 121: Accuphase or Gryphon

I use my MBL 111e's in an integrated Home theater/two channel music set up; and power them with the Bryston 28sst's monoblocks; much better dynamics and sound now with this extra power; then when I was using the MBL 8011's; which I thought underpowered the speakers...for theater; I use an Aerial CC5 center speaker; as I thought it would be difficult to get proper dialogue with an omni speaker for center channel duties; and it integrates great....sounds like you are on the right path; I have one Velodyne DD15 as a sub; but the MBL 111's have their own woofers; so I don't need as much extra base as you will.
Enjoy; and let us know how you solve these issues...

I use digital...I have a Meridian G-98 running thru the hd621 switch, which conveys some of the new aphodizing filtering; which makes my CD's sound much better, then back thru into a Meridian 861 v4.2. I also have Qsonix music server running digital out into the 861; the new hi resolution 24/96kz downloads from HD tracks played thru the Qsonix is actually better quality than red book cd as described above; but standard cd's thru the qsonix is just a slight step back from the g-98/hd621 sound..but it's all good. I also use the sony 5000es for Blue ray discs and home theater; the BD player handles the new HD audio info; and it gets run into the hd621 switcher; then into the Meridian 861 processor for awesome hd audio quality thru 5.1 speakers...I've not tried analog with my digital Meridian gear..it converts all signals into the digital domain anyway; but it also lacks a two channel audio bypass; so I can't get benefit from external dacs...

Other MBL owners have switched to the Bryston amps; see Dev's posts; with good results; and less expense than using MBL amps..the Bryston 14's or 7's might be a good match; but it seems that you found great synergy with the Pass 350.5...in an apartment; you seem to have your system now dialed in pretty well...