If you can get a high quality 4 channel amp, then you can use the Arcam to power the surround and Atmos channels. That would be the most efficient way, because your AVR should be able to drive the other channels without any issue, unless they are position further away than the front channel speakers and\/or have much lower sensitivity.\n\nFor the best specs possible for such an amp, I would consider the Hypex or Purifi based amps. Examples:\n\nAT52XNC Amplifiers (ati-amp.com)\n\nThat's the expensive option, but may be @AcuDefTechGuy could get you a good deal if you asked him;).\n\nOtherwise as others have suggested, the Monolith 200WX5 appears to be a good option.\n\nWith the questionable Arcam's preamp output, you probably should avoid power amps with less than 28 dB gain.\n\nIn all likelihood, a good quality class AB, or G power amp won't be the bottleneck in terms of audio performance specs.\n\n\nOn your point of avoiding power AMPs with less than 28db gain, does that just mean you have to boost your levels a bit in order to get the AMP aligned? Does that then limit the useful power of the AMP if the pre out maxes out at some point? My guess is it still can power fine with a lower gain but makes it a little more difficult in setup.