I took a quick look at the specs for the 788. You get 90w @ 8 Ohms and probably in the range of 140w @ 4 Ohms.
A quick check with a
power calculator tells us that at 80db listening levels AND with 15db of headroom for dynamics, you will need a whopping 19w. At 85db you are looking at about 60w. Push that up to an ear damaging 90db and you will need as much as 160W, slightly beyond the capabilities of the 788 into 4 Ohms (M80s).
Note: this includes all the power you will need for dynamic peaks in your favourite classical music pieces. For the most part you will be using much less power, probably in the range of 2-20w.
The 788 should be just fine.
