Based on the fact that you added a supertweeter, I feel it's safe to assume that you aren't into the, "warm" or "laid-back" sound that some embrace. I can thus recommend either V-cap Teflon/tin or copper foil caps, which are both very liquid and resolving. You should easily be able to identify the values, when you see the crossover. It's highly unlikely that Triangle used anything comparable, in the construction of their systems. You might consider replacing the internal wiring, with Kimber's 8TC, or 4TC as a lower-cost option. That's UNLESS Triangle used something equal in performance(again-not likely). Those should result in a more realistic midrange, although the burn-in might take awhile. When you get ready; I can recommend a way to burn-in the caps, prior to installation. Replace your 5AR4 rectifier tubes with NOS Mullard(Blackburn) GZ34's, before you do anything else. See what changes this swap makes. Your power amp already has Fast Recovery diodes, so- it SHOULD respond very favorably to HI-FI Tuning's Supreme fuses, and a power cord upgrade. I personally like Synergistic Research PCs, on my higher current draw components. Whether you bring dedicated service to the room, or do the fuse/PC upgrade first; one will make the other much more noticeable, regarding presentation. I brought two paralleled 10AWG runs(on a 20A breaker) to my outlets(equiv to 4AWG). Of course; my run was 125ft and damn near everything upstairs was wired to the same 15A breaker previously. Whatta difference that made! Some of this stuff is easily performed(though, perhaps, not exactly cheap), and should make noticeable improvements in your system's overall musicality(less grain/more organic & liquid). I've got a system that is larger than what my pitiful room should contain(result of an expensive divorce). If you can treat the wall behind your listening position with sound absorbing materials; you will enjoy better sound staging and a smoother in-room response(less standing waves/slap echo). No WAF issues, so my wall is mostly covered with Auralex(LENRDs in the corners). NOS Siemens ECC82 & ECC83 tubes(pre and power amps), from the 50's or early 60's, will also provide you with a VERY clean, but ballsy and extended response. Have fun!