First Sound line stages vs. The competition

I now use the FS pres del 2 with my VAC 220 sig amps driving the Vandersteen 5a speakers and am quite pleased, especially with the Vac synergy with the Vandys. I am listening to analog, now using the Aesthetix io mk. 2( non- sig version), Basis 2500,graham 2.2, Koetsu RSP cart.. Redbook CD goes through my AA capitole 2 player. I feel like my next step is to upgrade the FS preamp, although it seems to be a very strong performer in its price range, and I have not once regretted owning the unit. However, I am considering spending 2-3 times its price on a new Pre-amp to replace it and naturally feel that this will buy me an increase in performance. My problem is That I am considering linestages which may be difficult to audition before purchasing such as the Vac Phi 2.0, The Messenger, or maybe the Lamm L2 Reference, the Lamm of course being the only of these 3 that is line level only, with the Vac avail. as Full- function only and the Messenger avail as either Full- function or linestage only. I would like to reconsider going up the line with a FS paramount ,but this would be probably the least chance of all for audition and for this reason , I admit it has not been on my short list of contenders. If any fellow members have some direct experience with the Pre-amps I am considering , your feedback woule be greatly appreciated.