^^^
i totally understand, beside from the cabinets we have other tube stuff like akg solidtubes..eh, its just plain magic once you put in one of these. We also have a dbx566, put a telefunken in there...its better but still sheit imo (ii love my 166xl). We've hired a lot of stuff, nice but never suiting in the way that we'd purchase it except for the old focusrite stuff (isa) which is just very nice but considering that we dont invest that much into gear we'd wait off till the time was right. We actually wennt balistic over pre-amps after having all the good stuff rented...we made our own highly discrete pre amp, which has started beginning this year after buying some very nice vintage siemens pre amps/comp-limiters. My friend's dad at the studio is a prof in mathematics and a audiophile (this dude build an analogue oversamper in his cd-players, consisting out of tubes lol) and of course, is our secret weapon hehe. We buy mogami cables, read the specs, he measures with cold and notes that their specs dont match our measuring results. So after my boy bought the siemens pre's i kicked him and said "dude, i got you those on blueprint 3 years ago" like wtf pointing out to his dad. In reply, they overhauled the siemens and changed the powersupply. You'd think considering this is high end, it to be expensive but its pretty much half to any super modded 1073's you find. From there ive thrown in some schematics of vintage stuff and discussed features, i wont go into much detail as we plan on selling these babies but i can ensure that even the sm58 sounds rediculously sweet hehe but also this genius ran into some stupid issues that were never even fixed from original neve designs and also some features that arent even found on any high end pre to this date (wennt around redesigning phantom power) but i can tell you one big important feature, something which makes this unit completly versatile and that is the fact that it uses multiple transformers (the best you can find) which are selectable to adapt to pretty much all microphones. Ive come to conclusion that all these mic+pre combo's are bs, like a sony+teletronix is alway the way to go etc...bs and very annoying for you budget unless you're running a million buck studio and can afford to buy into all the typical "supposed to be" mic chains.
So most likely, modding really makes a difference but it can be hard to point out the changes as some things are really due to cirquitry design and possible interference making the gainstage more over class a/b than a class a(not to mention monitoring situation). So, if you dare, try one of the tab, siemens or old telefunken pre's, there are lots of mod and diy pages for these pre-amps and they do not compare to all bs gear that out right now.
I got this from audio pro on your mpa which sounds very interesting, besides, the dude does more than replace capacitors.
http://www.audioproz.com/AP.php?Article=36&Tab=Services