RCA Splitter - who, where

There are a couple of additional factors that need to be considered, which in some cases will be far more significant than your choice of a splitter. That is especially likely to be the case if either of the source components has a tube output stage (implying the likelihood of a high output impedance), and/or if ANY of the cable lengths are particularly long.

The parallel combination of the input impedances of the two amps, which will be significantly lower than the input impedance of either amp, has to still be much greater than the output impedances of the source components. If you let us know the specific makes and models of the source components and the amps it will probably be possible for us to look up the corresponding impedances, and provide calculations.

The signals seen by your new main amp will be affected by the capacitance of the cables to the amp in the kitchen as well as by the capacitance of the cables to that new main amp. If the output impedance of either source component is particularly high, and/or if the TOTAL of the lengths of the cables to BOTH destinations is long, upper treble rolloff of the signals to both amps may result, depending on the capacitance per unit length of the specific cables. Again, let us know the makes and models of the components, and also the lengths of all of the cables, and the makes and models of the cables if you already have them.

Regards,
-- Al

Thanks guys, particularly Al.
The sources are Rotel RCD-02 CDP, Wavelength Proton USB DAC
The main amp is a PrimaLuna ProLogue Classic
The kitchen amp is an Audiosource Amp-100
I was planning on the Audioquest Hard Y splitters with
Interconnects
Rotel->PrimaLuna;Kimber Kable PBJ 1m (Ls)0.770µH@20kHz
Rotel->Audiosource;Audioquest Sidewinder 2m
Proton->PrimaLuna;Kimber Kable Timbre 1m (Ls)0.493µH@20kHz
Proton -> Audiosource;Audioquest Sidewinder 2m

Cable capacitance will be no problem, considering the lengths that are involved. And also the fact that both Kimbers have relatively low capacitance, in the rough vicinity of 20 pf/ft. I couldn't find capacitance specs on the AQ interconnect, but I would feel certain that it won't be high enough to cause a problem, given the lengths that are involved, and also the fact that both source components have low output impedances at high frequencies.

I couldn't find an input impedance spec on the AMP-100, but the input impedance of the ProLogue is a comfortably high 65K. The Rotel CDP and the Wavelength USB DAC both have specified nominal output impedances of 100 ohms. However, according to JA's measurements of the Wavelength DAC in Stereophile:

The line-level jacks featured a low output impedance of 33 ohms at high and middle frequencies, but this rose to 1504 ohms at 20Hz, presumably due to the presence of an output coupling capacitor. The Proton should be used with a preamp having an input impedance of at least 10k ohms if the bass is not to sound a little lean.

As long as the input impedance of the AMP-100 is not less than around 12K, the parallel combination of its input impedance and the input impedance of the Prologue will be greater than 10K. The combined input impedance is equal to the product (multiplication) of the two individual input impedances divided by their sum. (12x65)/(12+65) = 10.1. And it would be unusual (although not unheard of) for the input impedance of an amplifier to be less than 12K.

So I think that most likely you'll be fine in all respects, and I'd imagine that the AQ splitter would be a good choice as well. To fully confirm that the input impedance of the AMP-100 does not cause an issue in conjunction with the low frequency output impedance rise of the Wavelength, though, compare the deep bass that you hear through your main speakers when listening to the Wavelength with and without the AMP-100 being connected.

Regards,
-- Al

Al, thank you so much for taking the time. You've gone far above what one could possibly expect. I'll follow through with your suggestions and I truly appreciate your time and opinion.
Kind Regards,
Jim

crutchfield and vanns both have Monster's upper end splitters on sale. I've used em w/ great results only w/ subs though. I agree w/ others here too. Really can't go wrong w/ Audioquest.