EV - I have mine installed on the inputs to the pre-amp. There was some previous discussion about attenuators on another thread (6 months ago?). Almarg had some useful input (as he usually does) on placement of the attenuators. I'm fuzzy on the details though I think input to the pre-amp was the way to go. There might be a downside to doing it at the amp...but I really don't recall with any certainty. Do a search. If I can find it, I'll post a link to that thread here. If we can't resurrect it, send an email to Al. He'll likely reply to the thread here rather than your email, but either way you'll get some good input.
ALSO - my read of your original post is that you aren't UNhappy with the sound but were mainly concerned the lack of volume control range indicated your amp might be too much for your speakers. Mofimadness addressed that, I believe. I can't tell you a new pre-amp WON'T improve sonics greatly AND possibly give you a wider control band on volume, but that's not the current concern as I read things. If I've got that wrong, please advise.
ALSO - my read of your original post is that you aren't UNhappy with the sound but were mainly concerned the lack of volume control range indicated your amp might be too much for your speakers. Mofimadness addressed that, I believe. I can't tell you a new pre-amp WON'T improve sonics greatly AND possibly give you a wider control band on volume, but that's not the current concern as I read things. If I've got that wrong, please advise.