It depends entirely on how your stereo is "voiced"...
Most speakers, and even some amplifiers, don't have a flat frequency response as they're meant to sound "nice", or to make up for other shortcomings.
So in practice they'd tend to have a hump in the 50-100Hz range to make them sound more bassy, and some now have a hump above 10KHz in order to make them sound more "hifi".
So using your hifi for monitoring is perfectly possible, so long as you're aware of what the relative sound of your stereo is.
I use my stereo for monitoring, but the amp's a Bryston (like the BBC use at Maida Vale) and the speakers are Leema - built by an ex-BBC sound mixer who also used to work at Air Studios and are designed to be pretty well flat from around 30Hz to 20kHz... However, it doesn't mean my mixes are any good - it's all down to practice and having a better ear than mine!