Barring some really cheap pieces of rubbish, there is no difference in sound quality between a decent hifi amp and a "professional" amp. Indeed, many hifi offerings are designed to be better in terms of things like THD and so on.
However, where there CAN be a difference is build quality. Truly professional gear is designed to pump out its maximum rated power in a hot equipment rack for 12 hours a day without breaking into a sweat. Few hifi products can claim that. However, as few home studios need that level of reliability!
One thing I'm surprised nobody has said: regarding the +4dBu vs -10dBV issue, it's not much of an issue. Don't forget that the "Volume" control on a hifi amp is an input attenuatior. As soon as this is turned down a bit, you're adjusting the input level to way less than nominal anyway.
(I guess that's another difference--professional amps are often operated with their front panel knobs turned all the way up and levels controlled on the mixer or whatever. Hifi amps are rarely operated this way.)
Bob