Parasound A-21 or 2250

My speakers Stratus Gold i. Pre Marantz AV-550. Source Panasonic DMP-BD60. Currently using B&K AV-5000 II (125 w 8 ohms, 185 w at 4 ohms) . Looking for better presentation, bass and dynamics which are limited with current amp.
Have no chance to audition before buying =(
Options are single A21 acquired used. Or first one Parasound 2250 refurb and then a second 2250 refurb for using one amp per stereo channel. System also doubles as HT.

Suggestions and comments are welcome fellow audiogoners.

Thanks Luis