I was told by Seven Oaks that they sound the same. The 5.1 supports stereo mode, stereo plus centre mode, stereo plus surround mode and lastly stereo plus suround plus centre mode, and each of these can work with or without a sub-woofer. In stereo mode the maximum power output is 75/120W per channel with 8/4 ohm speakers which is slightly less than the Arcam Solo Music. As I am sure you have noticed, Seven Oaks are doing them for £800 which sounds like a bargain. It lacks 4K which may be the reason for it not selling at the original price of £2,200 last year. You are best to listen to one for yourself and form your own views in my opinion.