low vs high gain

Generally, with variable gain on power amps, one sets the gain as low as possible for the max volume level one wishes without demanding more than whatis posible from the preamp. This gives the best SN at the speakers.
In your case, use the 26db if that doesn,t cause the preamp settingto be too high for the volume that you wish at the speakers.

Chris, only if your preamp is incapable of driving the amp to full output at the lower gain will dynamics be affected by the lower gain in the power amp. For example, if the gain at 32db settings means that .5 volts at the preamp output will drive the amp to full power, then 2.0 volts will drive the power amp to full power at the lower 26db gain. If your preamp, however, is incapable of producing 2 volts into the power amp, then it will not be driven to full power, hence 'lack of dynamic'. This not a problem, usually and therefore the more the signal is amplified before the power amp the better the SN at the speakers will be, especially with very sensitive speakers.
In other words, use the lowest gain that does not drive the preamp into distortion for the highet volume that you will be using.
Bob p.