New Cartridge choice

I think a superb cart considering your preferences (for more detail that whole lit from within with dynamics) is the Dynavector Te Kaitora Rua. There is one for sale now though I know nothing about the seller. It is one from the best DV makes and sounds very similar to it's big brother.

The Shelter 90x is nothing like the rest of the Shelter line but more in line with the Transfiguration and Lyra side of things. I also think it would be a nice choice.

Vik

Which K&K phono are you getting? Does it have the MC inputs and adjustable impedance? That could influence your decision.

Assuming you'll have adequate gain, the ZYX Airy 3 will also do exactly what you want, particularly the low output version. It needs a stable, non-resonant tonearm so my guess is that it would work well on yours. I've compared the top three ZYX's to a Koetsu Urushi and RSP. Check out the reviews next to my signature. (Both Koetsu's were easily bettered by the ZYX's for everything but midrange soupiness.)

Used ZYX's are somewhat difficult to find, but Mehran of SoraSound sometimes gets them back when people trade up. It's worth contacting him to ask.

One caution: like any cartridge with a line contact or micro-ridge stylus, a ZYX will only give it's very best if VTA/SRA are optimized. Your arm doesn't do that inherently, so if you don't have an aftermarket adjustor that might be in your future as you move up the performance ladder.

Well, I will give you what experience I have with both the Koetsu Rosewood Signature and the Shelter 90X.
(I have owned both and used both for significant amounts of time.) Plus my friend now has the Rosewood Signature Platinum.

I agree, that the Koetsu mid-range is incredible. If you like the Koetsu warmth, I would go with the Rosewood Signature Platimum. It has slightly better treble response and it will add the bass response that the Rosewood Signature lacks, although it will still be a little bit less than the Shelter 90X. (My buddy went from the Urushi to the RSP and he is very happy with the results.) The only problems with the RSP is that it is very expensive, even used, and its output is only 0.2mv, which requires a phono stage that has at least 70db of gain.

I myself upgraded from the Rosewood Signature to the Shelter 90X. The 90X has much better bass response, and slightly better treble than the Rosewood Signature. (In fact it is one of the best bass reponses I have heard.) It has a warm sound, but not nearly as much as the Koetsu. The mid-range is very good, but not Koetsu good, IMHO. The treble is well extended and pretty smooth. It is also fairly easy to drive (for a MC cartridge anyway), given the 0.6 mv output.

If I were grading the cartridges, I would give the Rosewood Signature a grade of B+.
The Urushi and the Shelter 90X would each get a A-.
(The Urushi's midrange is offset by the 90X's bass response.)
The Rosewood Signature Platinum would get an A.

The other thing I love about the Koetsu's is their lack of background noise. It has a very deep, dark background. The Shelter is pretty good, but not quite as good in this respect.

My next cartridge? The RSP.

My two cents worth. Good Luck in your search.