Upgrading pre amp advice.

@simonb : I've read about the PRE90, for it's price it's a no-go but it may be what to clinical and not as resolving AND full bodied as more expensive control amplifiers?

@fatdaddy2 : I already experimented with several setups and I think it's as good as 90% (okay, the other 10% depends of which music I am playing and I don't want to move my speakers all the time ; )

@oddiofyl : I have to think good about it (spending more as my budget is now, I can only spend it once ; )

@jdub39 : can you please tell me the differences you heard between the Ayre K-5xe- mp and the Musical Fidelity MS8 PRE?

@vinylshadow : DAC with great pre amp only is not an option because I also want to connect other sources.

@glenmschneider : I know the Grimm stuff very well but it's only where I can dream of (= unfortunately above my budget)

Buy once, cry once..   My most marked improvements with component upgrades have been upgrading the preamp.  

Speakers, sure the difference is easy to tell but the importance of preamp is often overlooked.  All of your sources go through it and it drives your amp.   

I also read very positive comments on the SPL selector.

Someone who has compared this pre amp with the Benchmark LA4?

I guess they are in the same league?

This older review (link) provides some insight on unity gain buffer preamps discussed earlier in this thread. A unity gain buffer does not need to be accomplished using op-amps as the McCormack unit uses FETs.  Basically, an active unity gain circuit allows a high input impedance and low output impedance in order to drive the cables and to provide a low impedance signal to the amplifier thus preserving the tonal qualities and dynamics of the source material.

Over the past 12 years, I have use a McCormack TLC-1 that was upgraded by SMc Audio.  To my ears, and in my system, it sounded better than the (around) 20 pretty good preamps I owned prior to the SMc unit. Those 20 preamps included the Ayre K-5xe, Benchmark LA4, and a bunch of other well-respected units like Lamm's LL2 and more.  I was recently fortunate to upgrade to Steve McCormack's SMc Audio VRE-1C (review links - 1, 2, 3), his statement piece which was designed based on the TLC-1.

+1 Linear Tube Audio 

It has all that magic you're looking for.