Comparing Phono Pre-Amps

Thanks for the suggestions.

I think I might try the cable route.

For the ground, can I simply send the ground to each phono-preamp or just to 1 one of them?

This really is just for comparison reasons not a permanent solution.

Thnx

+1 @ghdprentice but I also understand the OP’s desire to do quick A/B comparisons.  IME they can both be beneficial.  As a reviewer I used to start with quicker A/B comparisons just to point me to areas of difference I should pay attention to and then listen for those things during longer listening sessions over multiple genres of music to validate and nail my impressions down.  I found this to be an efficient, valid, and effective way to compare components, and as a reviewer you have limited time so anything that helps.  But that’s me, and everyone works and hears differently so find what works for you and just do it is what I’d say.  I know the inexpensive splitter I recommended is likely not optimal, but for 27 bucks it’s sure an easy and low-risk avenue to try, and if it happens to provide the OP with insightful info it could still be very valuable, especially if the quick comparison impressions coincide with longer-term listening impressions.  Just my $0.02 FWIW. 

+2 @ghdprentice 

I basically no longer do A/B tests.  I prefer to listen for long enough to something that I have a good sense of its sound.  Then listen to the other thing.  If changes are not obvious with that type of listening, I am no longer convinced they are all that important.

Regarding the use of any type of switching device, I would not want to assume that it has no effect on the cartridge loading.  I think you want to go straight from tonearm to phono stage.

Splitters may not be the ideal connection, but they are good enough to hear differences.

Like/prefer it? keep it? return it? 

friend brought his new tube phono to compare to my tube McIntosh mx110z's phono.

TT to splitter

splitter a. to his new tube phono, then to integrated amp 'AUX'.

splitter b. to my SUT, sut output to mx110z mm phono in/preamp out to integrated amp 'CD'.

switch integrated inputs 'CD' to 'AUX', instant comparison.

NOTE: volume differences might have to be dealt with. In my case, I was able to adjust the mx110z's volume to match the volume of his into AUX. Sometimes it is just a temporary pencil mark.

In my case, 3 arms into/trru SUT with 3 inputs and PASS for MM, we were able to compare MC; MM and MONO MM. I needed to adjust volume for their differences.

Yes, any of those switches, typically old video switches, 1 in, 3 out can be used backwards, 3 in/1 out. 

You still need to solve volume differences.