Koetsu Blue Lace Onyx vs. Coralstone

Diamond cantilever - yes, I think it is most definitely worth it. For those interested in the basis of my opinion, I am using the DC rosewood body with
- trans-fi air bearing tonearm, heroically regulated air supply
- NAS Mentor, machined Al / plywood plinth, new Wave Mechanic and motor
- Sowter transformers with nude Vishay loading resistors
- homebrew cost-no-object electronics
- multiple new generation Quad ESL's with reworked high cost electronics
- 80 KHz ultrasonic record cleaner

I was advised that the DC would harden the sound. I can't comment on a standard KRSP, but the DC makes the music uniquely smooth and elegant. My taste in music is "classical", by which I mean serious music, especially from the Renaissance. Polyphony is especially hard to get right - my system does it, and the DC is an important element thereof. The main difference between my system and live (acoustic) performance is slightly inferior leading and trailing edges - and that is the current research topic (turntable).

DC Fragility? Perhaps, but I have not, as yet, had an issue with that. Just make sure that if you use a coin as a standard weight for your stylus gauge, you use a silver coin, not one of the modern steel ones, as the platinum magnet is unexpectedly strong.

Update

DIY air bearing turntable with 45kg platter makes the Koetsu still better. Clarity without the edge, detail without noise.

Trans-Fi tonearm is weighted with brass weights and deadened with damping material.

And the silver Lundahl transformers don't hurt either.

@terry9 
Very curious about experiences with Koetsu and a silver Lundahl SUT, as I'm eyeing those options right now. Do you have the amorphous core LL1931/1941Ag or a LL1933/1943Ag?

I currently have a Bob's Devices Sky 40 and LL1931 (copper). With my Coralstone I find the amorphous core LL1931 to be much more detailed and transparent, which a much higher level of spatial information (really stunning). However, this comes at the cost of midbass punch, impact, and some of the organic warmth and musical flow the Coralstone is known for. So I was thinking of trying the LL1943Ag, which has a mu-metal core. But maybe the LL1931Ag is so good it addresses the flaws of the copper-wired version?

I find that the LL1931 pairs beautifully with a Shelter Harmony, btw (but the Coralstone is certainly the better cartridge). 

@mulveling

I have the LL1931Ag. I consulted the factory and they referred me to K&K, and after discussion, I took their recommendation. Very pleased.

Haven’t noticed any diminution of mid bass punch or impact. Some loss of sweetness, yes, I think so - but I recovered that, and more, by precisely torquing and aligning the cartridge. I concluded that the 31Ag was simply faithfully rendering the signal it was given.

Since you already have LL1931’s, you know that they don’t need anything but loading resistors and a box. That makes DIY SUT’s feasible for almost anyone, and makes the 1931Ag’s highly cost-effective. Speaking of loading resistors, I strongly recommend nude Vishay. To my ears, there is not even a competitor.

Good luck!

Thanks @terry9
My phono stage is a VAC Renaissance SE with the LL1931 built-in, and is chock-full of nude Vishays (I counted 36), including the loading slots. I’d previously borrowed a non-SE; the SE model’s Jupiter beeswax caps and nude Vishays make quite a positive difference. I figure I might as well go all-out to the Ag SUT at this point; agreed that the K&K prices are extremely reasonable! What loading value did you settle on for your Koetsu?