Just put AQ double connector on the output of my phono section in order to record to a newly acquired reel to reel.  I seem to be gearing an increase in upper mids...a little brightness I could do without.
Is it all in my head?  Can anyone suggest a reason why there might be a change in tonal balance? This seems to happen even when the signal is not passing through the decks circuitry; so it's flowing the same path as always.  Solid metal (no cable) splitter have a substantial effect?
F46ca363 bb03 4d2b 83c8 fedb4b3b4b25lwal22
Depending on the specific cables and components that are involved the effects you have noted may be due to one or both of the following, which are not caused by the splitter itself:

1)The phono stage is now having to drive a lower impedance (i.e., a heavier load) than before. When both components that are being driven are turned on their combined load impedance as seen by the phono stage equals the product (multiplication) of their individual input impedances divided by the sum of their input impedances. Which will always be lower than either of the individual input impedances, and may be much lower. That effect will most likely be no better if one of them is turned off, and may actually be worse if one component is turned off because the input impedance of the unpowered component may to at least a slight degree fluctuate arbitrarily as a function of signal level.

2)The phono stage is now having to drive the capacitance of two sets of interconnect cables, rather than one. The capacitance of the cables to the tape deck will affect the signal received by the preamp or whatever other component is connected just as much as the capacitance of the cables to the preamp itself, since it will affect the signal as it exists at the output terminals of the phono stage. This effect is most likely to be significant if the output impedance of the phono stage is high at high frequencies, and if either or both of the cables are long and/or have high capacitance per unit length.

Again, neither of these effects are caused by the splitter itself.  And FWIW I have used the AQ splitter in the past with fine results.

-- Al

Al, thanks. 
I understand now, how the the change came about.  I'm thinking a quality switch would be a better choice for my system, so there'd be only one interconnect and device being driven at a time. 
I hope I can find a 1 in-2out switch. Haven't seen one yet. 

Hi Lou,

I’ve had good results with the DB Systems model DBP-2JAU/5 ($110) listed near the top of this page. I've used it in a couple of different 2-in / 1-out applications, but it can also be used 1-in / 2-out among other ways. It is similar to the DBP-2J/5 for which a review and description are linked to, except that it has gold-plated jacks. For contact information go to their home page.

Another possibility, although it costs $359 plus options, is the Decware Zen Switchbox.

Good luck. Regards,
-- Al

Thanks Al, major help and much appreciated.   I'll give the db systems switch a try,  seems like the right way to go.  

Why not just connect your R2R output to your system to monitor when your recording and save all the extra wires and switches?
Trying to avoid frequently making and breaking connections.  Hard on the cables.  Also I like to add to an ongoing mix as a track comes on and fits.