Volume Control of K4102 Guitar Preamp into K4001 7W Amplifier

I am planning to use a K4102 Guitar Pre-amplifier to feed into a K4001 7 Watt Amplifier.

At what point should I add a volume control? Should it be on the guitar feeding the J1 input of the K4102 preamp or between the K 4102 preamp J2 line out and the K4001 input as shown in the K4001 assembly instructions on page 9? Guitars can be built with no volume control on it or a volume pot or a volume and a tone pot inline with the guitar output jack.

The K4102 preamp does have a trim pot (RV1) but that is a set and forget control to limit input so that volume is not boosted to a level destructive to speakers or headphones.

Additionally I plan to use a +12VDC @ 1 amp wall wart power supply with an inline 1 amp fast blow fuse to supply voltage to both the K4102 preamp and the K4001 amp. Do you foresee any issues with this?