Cary Audio SLP-05 or Conrad Johnson ET7 S2

I’m not in a hurry to add a preamplifier to my existing system which consist of a Brinkmann Nyquist DAC and a Decware 341.5 tube amp.  But…I do have the itch.  I’ve searched all over the net for reviews and comparisons but did not find anything persuasive.  I will purchase used and on Audiogon, each is available at around $6500.  Any guidance would be appreciated.