Putting a preamp on a integrated?

Do you mean physically on the unit or using only the amp section in the 6900? Physically on the unit is not a good idea because the preamp will impede convection cooling for the amp. Using only the amp section of the 6900 (which it indeed can do) is fine if the preamp you are adding is better than the built-in one - which would be surprising. I would advise against using a different preamp stage because IME, all my McIntoshes sound(ed) better with McIntosh preamps. Anyway, don't know if your question is answered but this is my attempt! take care -Arthur

The MA6900 has pre-outs AND amp-in so that the preamp and amp can both be independant. This is a rare feature in integrateds (pre-out is somewhat common but amp-in is definately rare) but allows lots of flexibility if it is ever desired. Some people may want to use an HT processor/preamp as the preamp stage and use the 6900 to power the front speakers, etc. Glad you love your 6900 - it is a very fine sounding piece and I would like to have one too! Take care - Arthur