Lack of bass with SP-9 MK3

I doubt that your unit is faulty.

Couple of possibilities. As you said, if you are comparing the SP9 to any unit with a contour feature engaged you bass will suffer considerably. Even if your contour feature was automatically adjustible with changes in volume, differences listening at low levels would be substantial.

Additionally the SP9 is balanced to the brighter end of the spectrum. The bass is certainly present, but the mids/highs are, IMHO, exagerated and will focus your attention on that part of the spectrum.

Tubes can make a difference. I would recommend that you try some new production EH 6922's. They will definitely add some warmth to your SP9. (I tried some in my SP10 a couple of months ago).

Hi: I had the same problem with a SP 9 mk2 awhile back ..Much too dry and brittle for my taste..I didin't keep mine more than a couple months.. I went to the Audio Research sp11 and found a whole different world..I actually feel the older SP6 sp8 sp10 and sp11 are still some of the best peices ARC ever made..They are all a little different in design but all share the same magic,with a little variations in each..I owned the sp6,sp8 and sp11 and fell in love with the sp11..Some like the sp10 over the sp11 and some like sp11 ( which i did ) over the sp10 ,but I feel that the sp10 and 11 the best of the group...These peices have detail and body ( and magic ) that the sp9 doesn't have.. Just my 2 cents.Hope it helps....

The are exceptions but thats pretty much the trade off. Take your pick if you rock, the soundstage depth wont matter much as it isnt existent in many pop recordings.

New tubes sound like a good start. Do you suggest ordering straight from ARC or somewhere else?

Do you think adding a dedicated subwoofer will help the issue? Though I'd think that if the signal is just not there, then there is nothing for the sub to reproduce.

Thanks for the suggestions.