XLR adapters for single ended cables

Has anyone tried using XLR to RCA adapters from the equipment's balance output or input. I have the XLR adapter in the DAC's balanced output, because my preamp does not have XLR connectors. I have RCA fitted cables. The sound improved greatly on the balance output with the XLR adapter than the RCA output. Should I reterminate one side of my RCA cable to XLR to get a better conncetion, instead of using the adapter? Does the signal get degrade through the adapter? Let me know what you think, and what you experienced, thanks.
I've used a Purist Audio Design female XLR to male RCA adaptor to use a balanced cable between various XLR outputs and the RCA-only inputs of my preamp, and it sounded great. Can't tell if there was any loss, because the only way I had previously used the balanced cable without the adaptor was with a different preamp. The Purist adaptors are supposed to be the best, and are also pricey, and they take a long time to make them to order. BAT also makes adaptors, but I believe only female XLR to female RCA. Those are supposed to be good also.
I would recommend using the built in unbalanced (RCA) outputs from your DAC to connect to unbalaced inputs of your preamp instead of adding an adapter to convert balanced (XLR) output from the DAC to unbalanced input of your preamp. Always keeping your cables as short as possible. Based on my experience, you would gain in lower noise performance especially when you are running interconnect cables in length of ~30ft or longer when using balanced I/O's but the sound shouldn't improve. The improvement you heard from the balanced output is probably due to ~6dB gain balanced output in comparison to unbalanced output, IMHO.

However, if you do us XLR connections, make sure your DAC follows AES guideline (pin 2 hot, pin 3 inverted, and pin 1 ground). Thus using pin 2 from XLR output for hot on RCA input.

Thank you Mgottlieb and Kichoi for your views. I also suspected the sound improved because of the 6 dB differnce. My DAC sounds better off the XLR output than the RCA. The DAC is a Sonic Frontiers SFD-2 MKII. Back then the reviewers also noted this, I found out the hard and long way. I had this unit for 6 yrs, and now justing trying the adapter and hearing the difference. I dont know if I am mad at myself or I should be happy. Maybe I am in disbelief and need someone else to tell me wheather I am right or wrong, thanks.