Yeah, a decent headphone amp is gonna make ALL the difference to you. Maybe pick up one of the Rolls units, they're pretty cheap and pretty good quality. You can also try Behringer (if you're ok with the brand). They make quite a few.
On the setup page, start by turning the output slider OFF. Focus on the signal going into Irig first. Set it so your signal hits the yellow every time you hit a note, and NEVER hits the red. I usually do this by playing an open A or E, because when you hit them hard they tend to cause the loudest signal.
After you get your input signal situated, THEN do the same thing for the output.
If you set up like this, you can still get a pretty clean tone at 100 watts through the B15R, and a bonus is that you'll get a little hair when you really dig in.
Of course, this is ALL dependent on having the input and output signal tweaked just right.
So many people dismiss Irig as junk, and they never bother to take the in setup. Irig is a very powerful tool, but it is NOT plug-and-play.
I usually hit a chord hard, so a D major chord on the 12th fret, so it will be an A, a D and a F#. This chord gives lots of energy.
So I do the same thing as Rip, thus keeping the input gain clean. But I usually use only the 100W, master dimmed and preamp gain.
Btw, we are all getting old here.... Some have hearing aid, some spinal stimulation machine... And me? I've hiss in my ears... Even the 30pin interface does not fix that!!
The iRig is a good interface, but it is limited as we know.
