Which Phono Pre?

I stopped looking at different brands once I purchased my first Audio Research Phono stage... you could get a used PH7 or PH8. They are very complimentary to analog and are truly audiophile quality and built for a lifetime. Over the last 40 years I worked my way up from SP3 every 10 years upgrading to now owning the world class Reference 3. Sorry to recommend something outside the box... but ARC is worth considering.

Raul is absolutely right. The Pass Labs is special and beautifully made. It will last a lifetime. The 4 Point is one of the best arms for a Koetsu. With the 11" 4 point you might have to add a little weight to the head shell as the Rosewood bodied Koetsus are lighter than the stone bodied units.
Soundsmith sells a great set of graded cartridge screws. With a Hi Fi News Analog Test disc you can get the resonance frequency right down to 8-10 Hz and your bass will be wonderful. The only other thing I can think of that would make an additional sonic improvement would be a low profile MinusK platform under the Firebird. After that I don't think you could do any better regardless of the money you spend. You are right at the point of rapidly diminishing returns. 

Dear @tablejockey : Here we are talking not opf tonearm/cartridge match in where I’m in agreement about that " determined by your ears ".

When we are talking of phono stage, at least for me, what I’m looking for is a neutral, accurated and very low colorations/distortions unit.
We need a phono stage that degrades the less the valuable cartridge signal and from my point of views the XP27 achives all those critical characteristics. The OP is looking for the best phono stage he can afford between those alternatives.

"" will have very tolerable noise levels.."""

Sorry but for me the best " tolerable noise levels " is NO noise levels ! I can see you are not to much demanding about, I'm the other way around.

R.

Whest and Pass are both really good SS. If you do a comparison you may pm me to try out the AudioSpecials Phonolab; it too is solid state and very low noise. Since I am a dealer for them I wont elaborate on subjective sq. If you read the German reviews tests show that you will not find much quieter at any price.
*if* the budget could stretch and *if* tube gear is acceptable to you then the Emia and the CS Port are both super awesome...

Raul, have you actually heard the Whest 40RDT?