Single input tube preamp

Great to hear and congrats! Thanks for the follow up, and really glad it seems to have the power to drive your very efficient speakers. Tell me you got it with the linear power supply.

Yes, got the LPS. Makes me wonder why every high end manufacturer doesn’t do that. Eliminates all the isolation and heat issues.
I’m not driving speakers, I’m driving a Parasound A23+. At the moment I’m going through my passive preamp with remote volume control. I’ll connect it directly later on and see if the passive is hurting anything. Keep you posted. 

@soix 

A little follow up. I upgraded the original RCA 12SN7s with some NOS JAN Sylvania VT-231/6SN7s from the great folks at LTA. They're sounding better every day. 

After getting a remote, I went directly from MZ2 to A23+. To have enough play on the LTA volume control, I had to use the volume pots on the amp. So I essentially swapped the volume control on Kara for another. After a couple of weeks, I've switched back to running the MZ2 through the Kara with better results. I think the RL volume on the Kara is cleaner than the volume pots on the A23.

So the amp runs with no attenuation, the Kara provides resistor based attenuation, and the MZ2 volume control is just right. I can always run the Kara wide open and only have the MZ2 volume control in the chain but I think the gain structure is better with some attenuation. I can also put the Valhalla 2, or a vintage pre without remote, into another input for another flavor. And I have the SS functionality on the Kara for non critical listening. I like it.