I am very much looking forward to krmathis' review of the SRD-7 Pro driving the SR-007s....
So, I've been listening to Joe Jackson's 1984 album _Body and Soul_ with the SRD-7 Pro driving the SR-404s. It's been fine... kinda milquetoast. I got about 2 mintues into the 6th track, "Loisaida", and could take it no longer... There's this part where it goes all quiet, and there's just piano, and Graham Maby's Fender precision bass. With the Pro box, I heard a piano and a pretty anonymous-sounding bass guitar, being played quietly... struggled to hear details I know are there... as soon as that part was over, I backed up the CD, switched to the normal-bias SRD-7, and BAM, I can tell easily what kind of bass guitar it is, hear the fret noises... then the horns come in and track builds up to a dynamic crescendo, with some great sounding drum fills. I FEEL the impact! There is NO problem with dymanics here! The X250.5 is actually working a bit, popping out of class A into A/B, pumping WAY more than Stax's reccomended 30WPC (instantaneous!) into the SRD-7. I worry about pushing the SRD-7 so hard... but now it's easy to tell that Maby is digging in hard on the strings of the P-bass during this part, rather than the anonymous-sounding boomy bass tone I get with the Pro-bias unit, which sounds like I've strapped a pair of 18" subwoofers to my ears.
I'm back wildly air-drumming, flailing my limbs around like a madman like I was with the SR-X/MK3, only there's BASS. With the Pro-bias adapter, the music just loses the magic...
The only thing I can really fault the SRD-7 normal bias adapter for is bringing out further the frequency response irregularities in the SR-404. Piano in the upper registers can be pretty painful. It's better reigned in with the pro-bias unit, but at quite a cost.
I should drag out my Sonic Frontiers transport, and use the AT&T ST optical cable. With my speaker setups and SR-X/MK3, this thing is deficient in bass and brutally harsh and detailed up top... might go well with the SRD-7 Pro/SR-404s. I've been on the fence regarding keeping this thing around as I don't really enjoy listening to it with any of my other system configurations... but now I have a feeling it might work here, and might be even better with the eventual SR-007s...
I really want to get ahold of a pair of SR-Lambda Signatures... someone convince nikongod to split up his FS system and sell the earspeakers to me!
edit: I was inspired to put on one of my many bass guitar reference tracks, Luther Vandross' "I've Been Working". Macrus Miller beats the s*** out of his Jazz bass on this track. The SR-X/MK3s was the most vivid I had heard it... before now! It sounds pretty awesome with the Pro box... but with the low bias box, it is freaking MAGICAL!