Help hooking up Alesis SR16 with Boss RC3 into head

[surfguy13]

I use a Boss RC3 looper a great deal and although it has a few basic drum sounds they are really very basic and the tap tempo drives me crazy.  So, remembered I had my 20/30 year old SR16 in the attic so got it down to see if there was any way I could continue to put the bass through the RC3 and into the amp but somehow incorporate the SR16 too so that I could record loops using the SR16s drums rather than the RC3s on board drums.  T

I realised that this was going to be a little challenging.  The RC3 has 2 inputs, input A and B with A being mono.  I put the bass direct into A and using the 'main right' output on the SR16 connected it to input B on the RC3.  The RC3 has 2 outputs, again A and B with A being mono.  However, the head only has one 1/4" jack input on the front.  So used an ancient old splitter jack (two jacks in and one out) in the amp's input jack and ran 2 leads  out of the two outputs on the RC3 into the two jacks on the splitter.  This actually worked but the volume on the head was almost halved.  

There doesn't appear to be any way to go direct into the SR16 and then out of that and into the RC3 so I'm a bit stumped; other than midi and I have never used midi before.  However, there are connectivity options on the back panel of the head.  Its a Behringer BVT4500H.  The rear panel has  a Speakon output and also 2 x 1/4" unbalanced outs.  Then 2 x 1/4" jack send and return effects loop and also a 1/4" power amp input and preamp output. Finally it has a Line Output with balanced XLR out, ground lift, level knob and pre/post button.  It also has a tuner out.  I simply have no idea if any of the above would allow me to connect the RC3 and the SR16 so that a) I don't have a major loss of volume and b) be able to use the SR16 through the amp and actually record bass and drums via the RC3.

I probably haven't explained this very well but any help would be really much appreciated!