will this really be an upgrade?

Was wondering how much of an improvement the following preamps would be over my existing B&K PT-3. Looking at the used market.

Quicksilver Linestage
Musical Fidelity A3CR Dual mono
Mccormack RLD-1
Looks more like a side step.
Trianglezerius, what would you suggest I do?
Look at the MapleTree tube preamp for around $650 brand new. It is the best preamp thta I have heard under $2K. You get a 10 day in home trail period so you cannot go wrong.
If you are also using B&K amp(s), then I'd stick with the B&K preamp. Consider using balanced lines if you're not already doing so. If you want an upgrade, look at speakers -- add a good subwoofer.
thanks Bigkidz.
I listed my post to try and figure out if their was any basic 'rule' on how much to spend on your next upgrade. I didnt want to end up buying something that would expose shortcomings in other parts of my system. My main concern was, whether to upgrade incrementally , or go the whole hog and get something like a Joule, Cary, etc.
using the B&K ST-2140 amp, and have two subs already.
In that case consider the Bryston BP26 preamp from a pro dealer.
Can you tube roll in that BAT? if so I would definitely do so first.......
My bad I read that as BAT LOL I personally like the anthems with tubes over the others you've mentioned.
Thanks for the advice
Musical Fidelity A3CR Dual mono will make that B&K sound like a toy. I had one for about a year and liked it quite a bit. I also owned the B&K for much longer.
Flemke, what then does the PT-3 compare to in your opinion; Rotel, adcom....