Balanced pre-amp?

melos sha-gold. great amp for both senn and grado plus nice pre stage.

Assuming you want to plug the phono in the Little Dot [I see you already have an unbalanced phono stage], and the amp does not do unbalanced to balanced conversion, you need one of two things:

1. A balanced phono stage. These are rather expensive with the cheapest one that I recall around $1000 [PS Audio GCPH]. This one will take the single ended signal from the tonearm and output balanced after RIAA equalization.

2. An SE-to-balanced converter. This is quite cheaper and could be done with either opamps or transformers. DIY is probably way cheaper. Transformers tend to give better results but are generally more expensive. Regarding opamps, I believe you can get the IVY output stage from TwistedPearAudio as that one can be used for SE-to-balanced conversion.

Hope that helps.

A switch would still not solve the issue of dealing with the single-ended signals.

To use the vinyl system with the balanced-only Little Dot, you need a way to convert the analog single ended signal to balanced. After you do that, a 2-to-1 balanced switch should do the job most wonderfully.

I like the TwistedPearAudio stuff and if you are DIY inclined, you can do this with around $300...

...you need to get the Darwin Selector, and an IVY to create balanced signals, and you could build that in a nice box for less than $300. Add a volume control and you have yourself a nice passive preamp that also converts single ended signals to balanced.

They are out there, the trick is that not all of them convert the single ended signal to balanced.

If you are generally running this into a balanced headphone amp, you may want to "just" get a single-ended-->balanced phase splitter to park between the phono-stage and the headphone amp (or source selector). If you are trying to do double duty for a speakers system, it depends more on the preamp, and what features it has.

I say just in quotes because converting single ended to balanced can be as easy or as difficult of a problem as you like.

There are a few inexpensive purpose-built op-amp based chips for splitting from SE to balanced. The DRV-134 is popular. I have seen a couple mini-reviews that point to the DRV-134 being lower on the totem pole for SQ than other solutions. you should not expect too much from a device with 3 (yes 3!) opamps inside that still costs less than $5... I have not tried this chip, but have had great success with phase splitting transformers.
do you mean an XLR-->RCA plug adapter?
This will work with some amps, but not others. Those adapters are generally meant to take a balanced signal from the source and get single ended out of it. Depending on all manner of things, the signal may or may not (more than likely not) come out balanced at the outputs.