- May 13, 2021
For protection passive attenuators are very useful, not only for the speakers but also the hearing.Long story short: no benefit in having a preamp, digital volume is as good as analogue. But PLEASE make sure the maximum output voltage of your DAC (I guess SU-9 has 4 or 5 volts with xlr out) does not put in clipping your amplifier. An amplifier in clipping can seriously damage your speakers. If this risk is possible, then check this post https://www.audiosciencereview.com/forum/index.php?threads/topping-d70s-fried-my-speakers.38706/ unfortunately chi-fi dacs can have buggish software that can randomly reset the volume to the max. In my case the topping D70S had a max voltage of 5v while my amplifier (Audiophonics Purifi) was designed to clip at 4v. The dac unpredictably set the volume to the max and my speakers got fried...
Here is a thread on the RME user forum discussing this along with examples of passive attenuators for balanced as well as unbalanced.
Level mismatch solutions - fixed and variable attenuators (Page 1) — Tips & Tricks — RME User Forum —