Upgrade VTL 2.5 pre to CJ P14 or ARC???

I have a VTL 2.5TL preamp that I really like; it also has built in phono stage which I use a lot. However I'm thinking of getting a diff. pre-amp like a CJ Premier 14, ARC LS-15, Cary, or maybe one of the BATs. Has anyone compared the VTL to any of those (or any others you'd care to recommend)? I realize with most of the CJ's & the ARC's I'd have to get a separate phono-pre; if you care to address that issue as well....Bottom line; does anyone have advice on how significant an upgrade any of these more expensive pre-amps & phono stages would be over the VTL. My other equip: ARC VT100MkII, B&W Matrix802-S3, CAL 25 CD, Rega P25. Thanks for any advice!
Steve- Have in considered having your VTL upgraded? With improved components (caps, resistors, volume controls, NOS tubes, etc... and improved power supply), you might not want to upgrade to another pre-amp. Of course, the added expensive may or may not be recoverable if you decide to sell the unit later. But if they are implemented properly, you'll probably never want to sell the unit. Just another option to think about. Goodluck.
Well, I had thought of just getting a used VTL 5.5....I didn't mention in my original post that I need another pre-amp for my 2nd system.....so it's either get a "better" (hopefully) pre-amp for my main system I described above (& putting the VTL in my 2nd system), or continue using the VTL in my main system & getting a cheaper used pre-amp like a used CJ PV10 for my 2nd system. But upgrading the 2.5 components is an interesting idea, Thanks.