I go way back to early dCS and the Elgar. Those designs had less flexibility in setting output line level voltage; 2 and 6V only. I wanted to use the Elgar directly into my active ATCs which have an input sensitivity of 0.5V ( newer models are 1V). You can already see without difficulty that I was likely to be in trouble in a smallish room.
So dCS sent me some in line -10dB XLR attenuators. When fitted ( amplifier end is best for lowest noise) SPL was reduced and I was able to set the Elgar volume control above -20dBfs. The tonal quality of the sound seemed unimpaired but the music was missing something. What? After further listening it was clear that all of the micro dynamics were MIA.
So I decided that perhaps the line attenuators sent to me could be improved upon and bought a far more expensive pair. Same result. Oh, BTW, I have since done the same experiment using Paganini and Vivaldi rigs.
There have been numerous discussions on other audio forums over the benefits of fitting passive attenuators and I would say that of every one person who gives a positive opinion 25 give a negative one.
So, try the 0.6V setting. But best of all, get an active preamp. You will find lots of discussion about that in the archives here with the majority voting for one rather than for direct connection. Direct connection has so much to recommend it intuitively ( why add circuitry? Logically it has to be better etc.). But in practice…