Zone 2 Music (2.X) amplifier help w/ balance control adjustment

I have a Anthem MRX720 for HT and more often use Zone 2 as my music source PlayFi (Spotify/Tidal,listening to alternative music and sometimes higher levels when I open the doors to listen outside on deck).  The 7.1 HT component is great (Revel F12 book speakers and NHT Ones for front height).  However, I need advice for Zone 2 music. I use a Nikko 890 integrated (70 wpc) to power Zone 2 with a pair of large Revel F50 floor speakers (these are NOT incorporated with HT speakers) . I would like to upgrade the Nikko and always wanted a McCormack DNA 0.5 (or something similar for $800ish) but have a few upgrade concerns:

1. Anthem 720MRX is my music source and does not perform room correct for zone 2 (BIG weakness, spoke to Anthem about it). This is a problem because the Left speaker is much further away and needs corrected.

2. The Anthem also does not allow me to change speaker level balance (L/R) for Zone2 nor does it have an pre-output for a Subwoofer (not a big deal but potentially limiting especially if Zone 2 had room correction/bass management). I currently use the Nikko integrated  for zone 2 power to easily adjust the balance.

One hind site question is:
Was there a better AVR choice for more robust zone 2? I bought it for HT room correction, nice sound with phone controlled PlayFi. However, it has grown to a  zone 2 music project and I am not sure how good the MRX720 DAC is since it is more of a 2.0 music system now?

Main question:  
If I found a power amp, would someone recommend a preamp like McCormack Micro Line Preamp for $300 or something similar with balance controls? 
Or recommend a $800 power amp (similar to McCormack) with volume controls and omitting preamp?
Or recommend an upgrade to $800 integrated amp with controls?

Thanks in advance!!!