XLR to RCA adaptors

That mostly depends on the equipment being connected. Are you using balanced components?

+1 @cleeds 

And just asking, why are you using balanced cables? 

If it is because you are running a long distance, say 10 feet plus, then using an adapter would negate most of the benefits a balanced connection would get you (mainly noise reduction).  In that case, then you might as well just switch over to a single ended (RCA) cables.

Adding a SUT so looking to use an existing RCA phono cable into a balanced Atmasphere pre that has a built-in phono. (Atmasphere is all balanced). 

I tried the Cardas a while back and eventually just had one end of the interconnects reterminated with RCA plugs.  If your system is significantly resolving and detail is important to you, then you will very likely notice a reduction in subtle inner detail and maybe more.   

rsf507 

... looking to use an existing RCA phono cable into a balanced Atmasphere pre that has a built-in phono

With that preamp you can use the RCA inputs and you'll enjoy all the benefits of a balanced connection.

Yup Ralph will tell you a MC cartridge with 0.25 mV or greater will work. Nope not even a 0.4 - 0.5 mV cartridge works with this phono. I've spoken to 3 other owners and all agree. 

Orchard Audio STEREO RCA TO XLR CONVERTER

https://orchardaudio.com/shop/stereo-rca-to-xlr-converter/?srsltid=AfmBOoprZDmh8_drDpMS2LvyQirwXmL42x-41ftsFWiZ-Q5rRYv8-X1o

awful expensive direct box that we use in the professional sound industry

Recently I brought about changes into my system, where Long Term Owned Power Amp’s are now a Balanced Design and after all the worries about loss, the end result is only gain for the betterment.

Another Change was quick to follow, where I put to use with the Power Amp’s a Balanced Pre Amp Design produced by a friend of mine. 

Another Change was quick to follow, where I put the Stacked Quad ESL’s to bed and let a new Dual Concentric Speaker take on the role of producing End Sound. These are as good as the Quads in many areas and also show the Quads shortcomings as well, especially in Low End and then upper mid and higher frequencies.

 Another Change was quick to follow, where I put a 300b Power Amp to use with the Balanced Pre’ Amp’.

For this I needed a XLR / RCA connector, which I bought from China at £10. It was only selected as an item if it had Copper Conductors. I can only say music produced with the XLR / RCA Connectors has been totally satisfying.

Another Pre Amp is now also in use which allows RCA > RCA to the 300b, even though the Pre Amp’s present different, both are impressive equally with End Sound Produced. 

I also fail to see where a extra £50 - £100 in a connector in such a situation is going to be able to substantially surpass my selection.

My experiences had, creates the Strong Suggestion, Signal Wire - Cable Connectors - Chassis Connectors, when swapped for a certain design will make a major impression of betterment over alternate options.     

https://www.ebay.co.uk/itm/325417134647

The DVA R2X is a single-ended to differential converter (i.e., unbalanced to balanced converter) for audiophiles.

https://avahifi.com/collections/accessories/products/dva-r2x

@lak I like the device in the Link, it certainly opens up options on interfacing other Pre Amp's into a Balanced Power Amp' System, which I am coming to terms with.

I suggest you also buy these inexpensive adapters, and see if anything you spend real money on actually is different, and if different, preferred?

https://www.amazon.com/COLICOLY-Female-Male-Cable-Adapter/dp/B07YNMNNZC/ref=sr_1_1_pp?crid=23ZR8SBNGIDN2&dib=eyJ2IjoiMSJ9.PamMNa2XvSC1_D3nfY86xfMU7AupbOQXvvogikaiQZ1l60FWsdvcPaG-N1UEp1XFAxoUatxy_qUm7CB0aBB6yX1pA4u9axrKg_9gQMz8AluTwbxZdvhh18X6OqECnF8hagRwDqX-osZZgZxeKqGErtc2fTbhylexLlAUMmvZfjTbRqHweenNTf3H0xSZyRT3moYrWJo8JzgNgieUAWl_r4FkWZubDQt2Kn0HgMKMbTY.kmTMeQ393OmG4Ne7KITOJo_szpvgpAsRSnz7KI0DlVQ&dib_tag=se&keywords=xlr+to+rca+adapter&qid=1751132555&sprefix=xlr+to+rca+adapter%2Caps%2C130&sr=8-1

try hard, get a friend to help you not fool yourself with expectation bias, keep one, return the other.

@pindac I recently purchased the DVA R2X to use with my new LAIV Harmony GaNM monoblocks. I received the DVAR2X two days after I ordered it and the unit works very well. I'm also very happy with the  monoblocks.