Use of Y connector rather than passive preamp

when not in use, these caps are a good idea. note center pin is removable

The Tortuga Audio LDR has an adjustable impedance feature.

The remote is pretty nice too. 

My listening is about 99% vinyl 

The Tortuga will allow you to hear what`s going on without adding anything to the mix. 😎 

Just to be clear, the DAC has good output and a volume control, so you could say it has a preamp built in. When using the DAC I will just set the volume on the passive pre to max. I hope this will sound essentially like cabling directly into the power amp. Buying a passive pre instead of a switch gives me the versatility of using it either as a passive pre, or as a high quality switch with a different pre/buffer on one of the sources. 

Have been looking into this. Some brands to check: Schiit, Mapletree, Goldpoint, Khozmo, Little bear/Nobsound, This covers a variety of prices and quality for stepped attenuators and potentiometers. You can also look into some based on transformers. It is important to keep the cable between the pre and power amp short, or the cable capacitance combined with inductance of the pre can produce high frequency rolloff. I have been trying these and they sound wonderful for some sources (eg my DAC with its higher power). Great improvement in clarity over my ARC - the detail in orchestral pieces is impressive. Bass is tighter. Depending on source you can lose some “fullness” in the bass (frequency response is fine). I hear this with the phono pre. I will definitely use a passive for my DAC, and may keep the ARC for the phono, Choice there depends on the recording (do you want clarity versus richer bass?). The impedance match between your amp and the pre is important for good sound. They say a rule of thumb is ratio of 100 or better. 

There are some inexpensive passive preamps that accept more than one input. I think Schiit has one, and also look for a used Tortuga as they come with remotes.

Just in case anyone checks this later: It can be ok to split an upstream signal so that it feeds into two amps, not ok to feed two upstream signals into the same amp input. If  they are on at the same time, bad things can happen. I thought maybe by turning on only one this could be ok, but that is begging for an accident. I think that some circuits can be damaged even if they are not powered on.  

Thanks for your help. Will give it a shot. 

My RCA splitters are the solid male to two female types....no clue if they're better or worse than Y-adapters, but they're working and sounding great.

I have used Y connectors over the years, never a problem.

People bring their preamps and phono stages here, we compare them to mine, sometimes using Y connectors, never a problem, everything sounds the same as when Y is out.

I use a Chase RLC-1 remote line controller to get volume, mute and balance for various units. No xlr. 4 rca in/2 rca out (identical front and rear from quad days). No one has ever been able to tell if it is in or out of the signal path. They can also work thru tape loops.

Your xlr equipment may have the advantage of a slightly stronger signal than rca's.

Cannot find a decent RLC-1 to buy now, current ones are missing the remote which is needed as no controls on the unit. they pop up from time to time, around $100.

This, ridiculously priced, shows the features