I just checked, and SR does offer a 15A Orange fuse. I would actually recommend the 16A to give you a little margin in case your amp draws more current at turn on. Any catastrophic event that will blow a 15A fuse will also blow a 16A.
Synergistic Research Orange Fuse
I have purchased this fuse for my line stage and power amp with great results. I would like to purchase another for my integrated Tube amp, however, this amp calls for 15A and SR only has a 16A fuse. Will this cause damage to my tube amp if I replace the fuse with a higher rated fuse? Thanks for any help.