Does such a preamp exist?

My pre simply has too much gain. I need a pre with 0 gain, but without the impedance problem of a passive;
So, this preamp has 0 gain input buffer, passive volume and sourse select network, then 0 gain output buffer...I wonder if this kind of pre exsists? If yes, please tell me, I want one volume knob keeps at 7-8 o'clock and already too loud.
Oh, one more thing, it must have balanced output...I know this is so difficult, I've searched everywhere and got no result.
I am not familiar with this product, but it does look promising.
What is your pre, amp(s) speakers. And how big is your room? Maybe the problem isn't the pre. To me your question reminds me of someone calling their dentist, and telling them they have tooth that hurts. Of course the dentist canoot tell them what is wrong without examing :)
For you information, unless you have an odd unit, your pre amp does have a gain control with a subtractive position(s), a unity gain position, and a amplified position(s). On my preamp, using an amp with a 1.5v input sensitivity, about 10 o'clock is unity gain for 1 source and 12 o'clock is unity gain for another.

What you need to do is to reduce the output gain by using in-line attenuators at the amp, say 12db, or see if your preamp mfg can reduce the output gain. What kind of pre-amp do you have?
The Levinson preamps like my 380S only apply gain when it is called for (about 19dB) based on the volume control position - from unity on down, the circuit actively buffers the inputs and outputs but applies no gain, and the sound does benefit. From what I've read, the forthcoming 320S will feature user-selectable gain including a 0 gain setting. All Levinson preamps of course are fully balanced with XLR I/O.
The Pass Labs Aleph P has variable gain and balanced inputs and outputs.
The Jeff Rowland Synergy preamps are balanced and have selective gain. Good luck.
Investigate at, splendid attenuators in balanced mode.

The site is worth a visit for didactical reasons too.
I don't know if they are available balanced but perhaps the Silver Rock might work for you.
Check out Manley labs. I believe this is what your looking for.