Audiotomb, there should be no issue if the volume knob is near the end or all the way up. Usually, all that a volume control does is attenuate the strength of the incoming signal, which the preamp circuit then amplifies by a fixed amount of gain. The only concern with the preamp circuitry should be the level of the signal input, the fixed (maximum) gain of the preamp, and the preamp's maximum output level.
If the signal going into the input jacks is 6V and you use the volume to reduce the input level to 1/10 (0.6V), or if the signal going into the input jacks is 1.2V and you use the volume to reduce the input level to 1/2 (0.6V), both are the same thing to the preamp circuitry. Whatever the input signal level ends up at, the preamp circuit will amplify that by its fixed (maximum) gain, which does not change with volume position.
I know that many audiophiles show a psychological adversion to having the volume turned all the way up, but as long as the preamp output isn't clipping or distorting, the physical position of the volume is a needless worry.
kind regards, jonathan
PS. There may be one or two unique preamps (such as Ayre's KX-R) where the volume does alter the internal gain, but such designs are quite rare.