This thread might help you explore the gain chain though is sort of jumping in the lake instead of getting your feet wet: https://www.audiosciencereview.com/...opagate-through-my-system.33358/#post-1165118
Reducing the volume in a purely digital sense, i.e. reducing the amplitude of the digital word, does reduce the output SNR (not resolution in the sense of the quantization level, but the effective number of bits is reduced). That is rarely a concern given the number of bits DACs have these days and is no different than what happens when the digital input signal itself is smaller ("quieter"). The noise floor set by quantization and analog noise does not usually change. SNR will reduce by about 6 dB for every bit (factor of two) reduction in the digital volume level. Given a dynamic range that often exceeds 100~120 dB, and a practical system dynamic range of maybe 80 dB, you can give up a lot without being able to notice anything.
Sticking a volume control in the analog path reduces both signal and noise so, if the volume control adds no noise or distortion of its own, then there is no net effect on resolution (noise, distortion, SINAD) after the volume control. The smaller signal into the power amp means its output noise is now a larger part of the output relative to the signal, so you do lose some, but again unless the amp's noise floor is too high (generally causing "hiss"), this is a non-issue. A lower signal level will have lower distortion.
The rule of thumb is to set the amp's volume at max and see if there is hiss at your normal preamp volume. If not, and if the preamp's volume range is sufficient for your needs (e.g. not sitting at almost no output so you do not have room to "turn it down"), then just use the preamp's volume control. If there is too much hiss, turn down the amp's volume control and see if the hiss is reduced. If so, then it is mostly from the preamp (or source), and you can reduce it by leaving the amp's volume turned down a bit and then again use the preamp's volume control to adjust your levels.
Reducing the volume in a purely digital sense, i.e. reducing the amplitude of the digital word, does reduce the output SNR (not resolution in the sense of the quantization level, but the effective number of bits is reduced). That is rarely a concern given the number of bits DACs have these days and is no different than what happens when the digital input signal itself is smaller ("quieter"). The noise floor set by quantization and analog noise does not usually change. SNR will reduce by about 6 dB for every bit (factor of two) reduction in the digital volume level. Given a dynamic range that often exceeds 100~120 dB, and a practical system dynamic range of maybe 80 dB, you can give up a lot without being able to notice anything.
Sticking a volume control in the analog path reduces both signal and noise so, if the volume control adds no noise or distortion of its own, then there is no net effect on resolution (noise, distortion, SINAD) after the volume control. The smaller signal into the power amp means its output noise is now a larger part of the output relative to the signal, so you do lose some, but again unless the amp's noise floor is too high (generally causing "hiss"), this is a non-issue. A lower signal level will have lower distortion.
The rule of thumb is to set the amp's volume at max and see if there is hiss at your normal preamp volume. If not, and if the preamp's volume range is sufficient for your needs (e.g. not sitting at almost no output so you do not have room to "turn it down"), then just use the preamp's volume control. If there is too much hiss, turn down the amp's volume control and see if the hiss is reduced. If so, then it is mostly from the preamp (or source), and you can reduce it by leaving the amp's volume turned down a bit and then again use the preamp's volume control to adjust your levels.