betavince,
Zone 2 does output analog AirPlay / HMG, but without the ability to control volume or listening modes. It looks like this may be your only option with the Pioneer VSX-1021-K receiver. Please disregard what I suggested might be possible with the other analog outputs on your machine.
I did have to switch the HOME MENU / System Setup / Input Setup Input Skip to OFF for H.M.G. to make it available with the INPUT SELECT buttons on the remote, and to choose the Manual SP Setup / Speaker Setup / Speaker System ZONE 2 setting.
All this is finally starting to make sense to me. I can't believe they haven't been able to figure out how to make more usable control systems and documentation. I guess part of the price we pay for such a low purchase price for such a sophisticated piece of equipment is in not hiring good technical writers. I mean, I have a background in digital electronics and a degree in Computer Science, and even a Master's, for crying out loud, and it's still embarrassingly difficult to get through this stuff. The troubleshooting section is especially dense.
I just wanna listen to some tunes, man.
I see you asked about treble in the RS 220 - sounds good to me as is. I listened to Kate Bush's Wuthering Heights with her high (coloratura?) soprano. Outrageous amounts of treble. Look out for an X-Curve setting in the Home Menu which will attenuate the treble if it is on. You could certainly tweak the treble throughout the Manual MCACC setup.
With my VSX-1121-K receiver (that has the preamp outputs,) I am going to order a
switch from monoprice to allow me to use the Front pre-out terminals to run both my speakers and the RS 220.
None of the Speaker B or Zone 2 solutions will allow for everything to be controlled from the remote.
BTW, in case you haven't seen it there is a Pioneer VSX-1021 Owners' Thread
here.
Good luck,
Hal