Help with upgrade from Marantz 6011

Do you listen to multichannel music or is critical listening more 2-channel?

Never listen to multichannel music.  That's all 2 channel.

I’d keep the Marantz (it’s probably fine for HT duties) and buy a good stereo integrated amp and incorporate that into the system.  By hooking the 6011’s front L/R preamp outs to an unused input on the integrated (or HT bypass if it has it) and then connecting your 705s to it you’ll have a pure 2-channel rig within a HT system.  When you’re listening to stereo the Marantz is completely out of the signal path, and you can switch between stereo and HT simply by changing the integrated’s input.  If you’re looking to up your 2-channel performance, this is the best and most cost effective way to do it IME.  Hope this helps, and best of luck.

Thanks for the advice I really appreciate it.

What do you think of adding two 5 channel amps?  I found on CL near me someone selling 2 Rotel RMB-1085s for $900 for the pair.  I can use the Marantz as a processor and then the Rotels to power my setup.

Will this work?  I'm ok to buy used just trying to sort through the large number of options.

Thanks again

The RMB-1085 are Class D amps using switching power supplies.  I had a friend who owned one briefly and the sound was somewhat boring and lacked involvement.  Having 10 channels isn't really needed in your system.

I think you'd be better off buying a new Outlaw 7000x for $999.  It uses linear power supply with Class AB amps boards at 7 x 130 watts per channel.

If you were willing to up the amp budget some, I'd look at the Monoprice Monolith amps.  You could do the 3x200 for $1249 or 5x200 for $1499 (and then use the receiver for any remaining surround speakers).