TUBE or S/S Phono Amp with an all s/s system?

I looking for a phono amp with mm/mc (high output) with better than average gain. I'm using KreLL pre & KreLL amp, cartridge is Grado Reference. I understand output impedance is something to consider when trying to match which way would you go, tube or s/s for phono amp? What specs should I be looking for?

KreLL amp input impedance > 47K
KreLL preamp input impedance > 47K / output impedance 10ohms

I'm quite "green" as far as "tech" talk goes, so I'll be the first to admit that I have a deficiency in this area.

Thanks for your advice,

(technical specifications deficiency syndrome)
I had a system with a Krell KAV 300i and an Audio Research PH-3 and the Grado Reference. It was a great match. The PH-3 (or PH-3 SE) is a hybrid FET input 6922 output. I am still using the PH-3 and the Grado, but not the Krell as I have moved on to a system with high efficiency speakers.

Don't worry about the impedance. The important thing is that the input impedance of the follower stage be higher than the output impedance of the driver stage. That's pretty much guaranteed with any pair of high end components. You may want to play around with cartidge impedance matching at the phono preamp, but it too is not critical and often requires soldering in a resistor. I've done a couple of experiments but the Grado Reference seems to like the PH-3 the way it comes.
The typical rule of thumb is that the input impedance of a device should be at least 10 times the output impedance of the device connecting to it. If the Krell has a 47k input inpedance then the Phono preamp should be less than 4700 ohms. This is amazingly high and I don't remember seeing any preamp with an output inpedance even approaching 4700 ohms. You should therefore be OK with any phono preamp that you like sonically. Wally name. Thank you, this is good to know.
Hey John, wanna sell? Thanks for your advice.
I'm happy with what I've got at the moment. However, I often see the ARC PH-3 for sale on Audiogon at reasonable prices.
There is no simple answer... much depends upon your system. Since you're into Krell now, you've got a certain sound to your system (which in this case depends upon the vintage of your Krells).

You could pick a phono preamp based on a desired coloration, or you could just get a Krell front end. Some of their phone stages were pretty good actually.

Much depends upon your turntable/arm/cartridge combo too.

I'd lose the Grado myself... to me Grados are always midrange heavy and lack top and bottom. Shure, on the other hand is all top and bottom, and no mids (just an historical reference). A nice MC would be the thing - then the phono preamp would start to really matter.

Personally, I'd prefer a good Audio Technica or Dennon cartridge over the Grado (even improved as they are these days).

Ymmv. These are only my opinions... strictly subjective.