Mphnkns, Please don't infer from my inquiries about what you have or have not done that I imply that you have not covered your bases. I merely ask about your situation as a form of trouble-shooting so I can possibly help out.
As far as describing my First Sound as having "leanness" or being "edgy," those terms would be almost the farthest from my impression of all of the First Sound models I have heard. I would describe the sense of detail from my First Sound as more subtle and lifelike than many other High End pre-amps: CAT Ultimate, Lamm LL2, and ARC Ref 1 MkII---all of which I auditioned in my system for a few days. With the FS, I would say that the details seem to just occur in the flow of the music without forcing them 'in your face.' The sense of transparency, with a well-setup First Sound, strikes me as clear and unveiled with little electronic haze or interference.
I am not familiar with the earlier versions FS units so I can't comment on greater power from the mid-bass on down one way or the other. I have learned that working with two 20-amp dedicated lines, FIM outlets, and Silent Source power cords has helped out a lot to realize what the FS can do---and I am sure I can do better. Likewise, using wood shelves and Aurio Isobearings have enhanced the performance of my rig. In my system, the bass power and dynamics are big and satisfying.
You mentioned about something a long the lines of the Nordost Valhalla may not agree with the FS but that you did try other interconnects. Can you be more specific? What other interconnects? Did change out interconnects both upsteam and downstream from the FS pre-amp? Have you listed your entire system somewhere and is it current? I'd like to explore your case more, but I would need your entire system setup description---including your room---to go much further if you would like some help on this, that is. You have said that you've tried various power cords such as Nordost, Shunyata, PS audio, and Transparent. Did you make these power cord substitutions only on the FS or elsewhere in the system as well and exactly which models did you used? (I have actually heard the Shunyata Diamondback exhibit a slight "bite" in some systems.)
I assume that you know more about HiFi that I do. I assume that you have a better ear than I do. It may just work out that another pair of virtual eyes and ears focused on your system may prove useful to you.
I tried Nordost Quattro Fil with the First Sound. Not good. (I would say the sound was edgy and lean with Quattro Fil, as a matter of fact.) I ran Nordost SPM speaker wire for two years. With the Audible Illusions M A3 in the system, the SPM was fantastic; with the First Sound, I prefer Mapleshade Double Helix Plus, or Audience Au24, or best of all, Shunyata Lyra speaker wire. Even though the speaker wire is a few links downstream from the First Sound, it mattered a lot when I changed to the FS pre-amp. Likewise, changing the power cord on the CD player almost does more that putting that same power cord model on the pre-amp. This stuff illustrates why it would be helpful to get your whole system's list and description. E-mail me off line if you want. Totally understandable if you don't want to go into it all.
This is the combo that's working for me these days:
VPI TNT 3.5 TT/SME V 'arm/Benz Micro Ebony LP cart'/Lukascheck PP-1 Phono stage; Ayre CX-7 CDP (running RCA unbalanced); First Sound 4.0 w Paramount Plus Upgrade; Cary SLAM-100 mono power amps (running in triode-mode Push/Pull at 95 watts); Coincident Super Eclipse (original version, 6-Ohm instead of the standard 14-Ohm); Arcici Suspense Rack; wood shelves and Aurio bearings; Audience Au24, or Shunyata Lyra speaker wire; Two dedicated, 20-amp AC lines; Silent Source Signature power cords throughout; 12.5 x 17' room with acoustic foam on parts of all walls except the speaker end. (LEDE config for now); Speakers fire down the long wall; Speakers are positioned about 5 feet from wall behind them and about 2.5 feet from the side walls. Floor is wall-to-wall carpet over concrete.
