70 dB may be too low for good listening. I'm sure recordings are mastered at significantly higher levels than this. And our hearing response is level related. The lower the level the poorer our hearing at low and high frequencies(I seem to recall flat is at 100 dB). So if you listen at levels lower than the recording was mastered at, the level the mastering engineer set his sense of octave to octave balance, you're missing out on lows and highs and that probably results in the loss of excitement.
Too much power?
I have a wonderful system with a great amplifier, and yet auditioned a more powerful version of the same amp. It indeed seemed to have more punch and drive, but at the expense of playing it a bit too loud. As my current system I rarely play over 70 db, since it’s perfect at low levels. I wonder other than bragging rights, what does more power get you? Since we aren’t here for PA style sound, is there a reasonable limit to how much you will benefit from higher power/ more expensive and? Especially since tire just using one watt most of the time?