I do have it wacked up slightly in regards to the fronts but not by much; I wouldn't say it's quiet at all with a sensitivity of 91dB. Maybe yours is slightly faulty? My m34s went like that for a while and when I modded them to m34is, I noticed the removed wires were pretty dark with oxidization. Made a huge difference to the sound too. Then again, that might just have been down to the m34s having poor internal wiring. Is yours a m3c2 or m3c2i?
I bought mine off ebay for £40, thinking it was the m3c2 but when i got it, it was the i version. Saved me £20 in a new crossover