This Pre-Amplifier circuit is a minimalistic design, a.o. inspired by valve design, which should help sound clarity. With 5 transistors, it has 0.1% distortion (expected from 60dB loop gain) up to 20kHz, input range= 320mVeff, and gain= 10x. Next, with no transistors added, I designed a Loudness control for it. Of interest especially for the Treble, by a resonant circuit!, which will please the young ears. It makes the gain range adjustable: 3x - 10x, to circumvent a known difficulty of Loudness.

Pls refer to the attachment, under 'Project Elements' below.
Here is the introduction, and 2 of 5 schematics:

An audio pre-amplifier is meant to drive a power amplifier and does provide the controls, the knobs.

This Pre-Amplifier circuit is a minimalistic design, but without compromising sound quality. The minimalistic approach, a.o. inspired by valve design, of a single (and special) feedback loop, a single input transistor (JFET) and low transistor count (5#) should even help sound clarity.

Distortion is 0.1% (expected from 60dB loop gain) up to 20kHz. 

Input range= 320mVeff; gain= 10x.

The circuit and a description of its operation is presented in Part 1.

Next, as an option, with no transistors added, I designed a special tone control circuit for this pre-amplifier, known as Loudness control. Which is, to my opinion, of interest especially for the Treble which will please the young ears. (Maybe this makes it less difficult to listening at a lower volume.)

Addition of my Loudness circuitry makes the amplification range adjustable, 3x – 10x, to circumvent a known difficulty of Loudness control.

 The Loudness control circuitry and my version of the theory behind it is presented in Part 2.

Also a cheaper version of the complete circuit is proposed (with full performance).

I have built the circuit as per Figure , and it is working fine. I do not have equipment to measure distortion or a frequency characteristic.

Simulations show that the design is robust against component variation.

I have put down some more information, it’s available – questions are very welcome!

Figure 1: Pre-amplifier 10x, with Volume- and (full) Balance-control. All by a single(!) gain stage

Figure 6: The pre-amplifier with economical(!) Loudness calibration and Balance control

Full text in the attachment below.