Running Two TT into one phono input, best options?

Haven't used the decware, and other than changing the gauge of internal wire not sure what could make the difference for regular and low level versions

As its 100% passive it uses a mechanical switch. If you want to geek out you could ask them what switch they use (probably Elma or Seiden...)
In theory gas sealed relays (still silver contacts) might be desireable in this application. Manely skipjack comes to mind but thats a lot more money. Iirc Khozmo (of attenuator fame) makes one on request thats not so costly...not sure what relays however...

Goldpoint makes great switches.

https://goldpt.com/index.html

In my main system I have two turntables and two phono stages. I’ve considered getting a phono stage with two inputs. A switch might be a lot cheaper!

Considering the signal levels coming out of a cartridge -- even a MM one which is high compared to MC -- I'd opt for a small phono preamp and feed its output to one of the auxiliary inputs. You might look at something like the Schiit Mani (only $130). It has a single stereo phono input, adjustable for MM or MC, several levels of amplification, and a single stereo line-level output.

Now you're set:

1. Phono 1 for TT 1
2. Phono 2 for TT 2, and
3. Aux 1 for TT 3

There are literally hundreds of simple phono preamps similar to the Schiit Mani ranging in price from ~$50 all the way up to ~$10,000+ -- for just a phono preamp! A quick google search for "best phono preamps" will bring up dozens of alternatives at a wide variety of price points..

Emia makes a very high quality triple SUT followed by relays for a 3 into 1. So the MC signal is up in level a bit before the switch happens...

There’s no perfect solution SQ wise. Can’t you use/try two Y splitters? Cheapest alternative.

Slaw
I did think about that but I also thought that was likely to be the worst solution for signal loss/hum.

But I guess it is worth a try for sure.

weh51nc
Sorry I should have been clearer, there are NO SPARE inputs left on my amp and I really want to use the present phono for all TT if possible.

High grade switch in a box with high grade RCA jacks. Goldpoint switch, or better. etc.

There will be degradation from the extra cable, switch and RCA jacks on the given box, on the desired turntable, vs the one not connected by the switch.

The y splitter is probably among the worst sounding. as the second ’leg’, which runs back to the unused turntable, will inject notable amounts of unwanted and almost ’floating’ LCR residuals, as noise.... into the tiny phono signal and make a mess out of it.

As an analogy, think of a racing vehicle on the track, with really good capacity to get around the track, and be competitive. This is your turntable, the one being listened to. Then add two or three 20 foot composite rods that stick out of it and weigh about 250lb each (some unspecified flubbery-floppy great mass), and float above the ground (at various angles, like some really big porcupine quills) and are moved about as the car moves around on the track. This is the shut down and not listened to but still connected turntable. Imagine how this fluttery, discombobulated, flexible and self resonant mass, will heave the car about, and totally ruin it’s capacity to get around the track. It will get around the track, sure, but it will be notably compromised. That is what a parallel connected but not used turntable lines, connected via a y-splitter bit of wiring -- will do do the tiny phono signal on the ’desired to be listened to’ turntable.

With the switch, that extra noise injection is all neatly separated, but some can still come in via the separate turntable ground, unless even that is made independent via three switched aspects, not two. (isolate the positive, negative and the independent ground wires of the two turntables via a three contact switch, not the normal two.
Actually..what is required in this passive arrangement...is a 5 point switch. Neg-pos for each channel and the ground as well. So the switch has to be a 5 contacts switched’ kind of arrangement. Everything lifted and separated. That darned phono signal is so small, it is easily affected by any connectivity in any way. Just like trying to measure micro signals in a ted bed set up. All this switching and/or separation would be the norm. Not even a question. It is simply done as it is known that this would be a serious and critical issue.  This turntable connectivity issue...is no less critical.

You’re looking at about $200, or more, to get it done right (parts cost alone, never mind the build). At least, as right as can be, relatively speaking.

Luxman LINE selector is what you need. 

Chak
I can find plenty of line level input switchers but as I know and Teo points out it is those tiny little signals we are dealing with that are the problem and oh so easily degraded because such low levels.

And I do not want to be trying endless solutions rather get it right first time, hence this thread.
So far the only unit I have seen that specifically states for low level tonearm use is the Decware unit although as Solypsa says it would be interesting to know just what they changed to make it "low level" compliant.

I may just send them an email first.

this is an example of a ’half lifted’ signal switching box. It is not preferred for phono switching. All inputs and outputs share their ground noise as a signal injection. Fairly unnoticeable for line level signals but probably noticeable for phono signal levels.

In proper phono use, the signal is balanced and the negative floats and the ground is separate and involves shielding as a concept and execution.

Some cartridges ground the negative, which is..not perfect, as concepts and execution goes. Many a cheap MM is done this way. Just to avoid hum issues in common cheap design, when the given cart is applied in a given system.

Again, the minimum of a four point switch and possibly a 5 point switch. Four and six point switches are widely available, five would be rare. Buy the six and don't use the one extra, easy-peasy. Goldpoint makes these, as do others.

Then the switch box itself, sheer size and mass can get into ground noise and ground noise injection problems.

Uber, If you are hoping for someone to tell you there is a perfectly transparent switch to solve your problem, you are hoping in vain.  I do know that Dave Slagle of EMIA can make you a fantastically good switch to solve your problem, but even he would probably not want to claim it's going to be perfect.  Using two Y adapters is absolutely the worst idea, IMO, because that does crazy things to the impedances seen by both the two cartidges at one end and the phono stage at the other end.  I wouldn't go with something cheap in hopes it will sound great.  When you come right down to it, plugging and unplugging ain't so bad.

Lewm
I do not expect there to be a perfect solution I agree but was hoping for some opinions that might be workable.

So far I have three considerations.

1/ The Decware switch with low level tonearm inputs. Would like to hear a reply to my question to them about what they changed first but it does have a 30 day money back guarantee.
2/ A Denon AU-320 SUT. This is a unit I have owned and used in the past with great results, it has 2 inputs, 1 output and is switchable from 3ohm to 40ohm to straight pass through. I honestly did not notice any readily audible difference when I last used one.
3/ A fairly cheap MM only phono stage to run the Rega mono table into and remove one of the tape decks from my system thereby freeing up a single ended input. Then both the 401 and the Avid could run into the Goldnote PH-10 phono.

I also went thru this recently, started a thread, found a few options, members added a lot to the discussion and suggested choices

https://forum.audiogon.com/discussions/phono-eq-small-inexpensive-two-phono-inputs

For MM, any simple RCA a/b switch will do it, I had an old small Sony Video Switcher, a,b,c,d in, 1 out. Best arm/cartridge direct to phono 1, a/b switch to phono 2 for the other 2 arms.

Then I decided to enter the world of Moving Coil

Any Step Up Transformer (SUT) with a combination of 2 selectible inputs, and PASS will do it, that lets you keep using your existing preamp’s phono, 1 direct, 2 thru SUT.

I got this, 3 selectable inputs. I love it, versatile options for MC, and PASS for MM, separate selector for the 3 rear inputs. You could run all 3 arms thru this, then into your Phono 1 input, use any combo of MM/MC, 

https://www.ebay.com/itm/Fidelity-research-FR-FRT-4-Toroidal-Transformer-In-Excellent-Condition/333648114135?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Luxman made switches under their top class turntable as as option to connect phono cables from two tonearm to one little box (located under the turntable). It was made in the golden age of analog for use with phono cartridges of that era.

A separate Luxman Line Selector Box is very easy to upgrade with modern high-end components (and a bit of soldering skills). I've seen this box in use with high-end tonearms, can't remember, i think it was on youtube. I believe this box is a good quality. 

The best solution is a phono stage with as many phono inputs as you need.

This was the reply from Decware on the changes to their box for low level tonearm inputs.

" Kevin, for tonearm applications we do not add the splitting resistors on the dual output jacks. Nothing internal but silver wire and silver switch."

For now I have decided to take option 3 from my short list and will be running the Rega mono table into its own simple MM phono and into a single ended input on my BAT.
Thanks to all for there help here

I decided to play safe.

Fed both the 401 and the Avid with MC carts into the Goldnote PH-10 and bought a Vincent PHO-8 just for the Rega with mono Ortofon MM cart and feeding that into a single ended input on the amp.

All works well sweetly and in all honesty all TT now seem to be quieter at the speakers, quite considerably less background noise.
More than likely due to rerouting of cables while rearranging than anything else I think.