Use AmpliTube 5 iOS/iRig HD 2 with my Spark 40 amp

[Mcknz961]

I'm an old guy, recently retired and I've got all this stuff (AmpliTube 5, AmpliTube 5 iOS, iRig HD 2 & Spark 40 from another manufacturer) which I can barely use. Unfortunately IK doesn't make anything like the Spark (to my knowledge) but I'm a Bass player and my IK stuff offers me an Orange AD 200 plus effects like the envelope follower, bass octave, etc. that Spark can't match. So how do I (living on limited income/SS) use what I've got together, or in other words bypass the Spark part and plug in my IK stuff if possible? Maybe someone knows a good YouTube channel that goes slow enough for an old timer like me that was trained in analog electronics but sadly my digital knowledge drops off after Windows 7 (oops!)

[Mcknz961]

So got to spend a little time today between football games and pro wrestling to mess around a bit. Found a 3.5mm TRS cable in a drawer and seems I just plug in the iRig and bypass all the Spark amp's controls save for a tiny pot marked "music volume" so it's just a little FRFR speaker (I'm guessing.) Is this correct? Seems to work.

I am finding the indicator light on the iRig to be a bit touchy. I seem to have to run the input almost full out with a (passive) bass. Would I benefit from running some kind of small preamp pedal prior to the iRig? I don't have one but I've heard good things about a model by Xotic or perhaps there's a better (cheaper) solution I don't know about?