Preamp has too much gain

The electronics should be run at the highest possible gain, at a given supply voltage, where feasible. For example, if the line stage is designed for 20dB of gain, and you run it at 5dB, the THD will go up tremendously, and the circuit may even become unstable. The higher gain also gives you the best S/N ratio.

It's the right way to pad down the signal level, then to lower the gain. The noise in the system is typically 'White', so the less gain, the less useful dynamic range.

I also had a gain issue. I installed rothwell 10db attenuators between my cd player and pre-amp and that solved the problem.

Chuck

The electronics should be run at the highest possible gain, at a given supply voltage, where feasible.

I don't understand. How would you lower the gain of a preamp without major reconstruction? THD comes from operating an active device in a non-linear manner. The operating point (bias) of the active device determines where you are on the curve and this isn't really related to gain so THD really isn't related to gain except in the sense that it will increase if you allow the signal to become so large it swings into the non-linear portions of the device's curves. It's a bit more complex than that since bias and operating points can affect gain but that's the basics. Maybe I'm missing something here.

Mark Levinson superb 326S preamp allow you to adjust the gain of the inputs from 0, 6, 12, and 18db. So, depending on your amp and speakers you can match the gain that brings out the best of your source. Your room acoustics will also play into it. With my McIntosh amp, the 12 db. gain settings sounded the best. Now I have a Mark Levinson amp and the 0db setting is very enjoyable, imaging is stable and in place and solid, bass is tighter, brass and such as the correct bite. Vocals sound so real you can see the artist face in front of you. the other settings sound good, will give you more upfront bass and such but you lose that coherency of the overall sound. Things just sound right at 0db, I like 12db if I want to have a bigger fatter sound with more upfront bass. The 326S at 0Db gain setting is just sweet, classy sounding, sounds like a gateway to the recording. Also, the way the ML volume control is designed it adjust to the gain setting so the old ways of thinking that a preamp gain should be low enough to where you turn the volume control almost all the way up, ML is way past that old way of how volume controls were designed back in the day. The best preamp I've owned tube or SS in 40 years. 

SPL Phonitor 2 Pre/HP also allow gain adjustments and is transparent zero coloration, you hear the actual source material. It is studio equipment.