"...One tree blooms into many branches so that many birds may roost to be roasted...."
I'm not sure what the Alesis 150 is; however, if you had a can amp, you would still need to plug a 1/4 inch stereo plug into something or somewhere in order to hear whatever is being recorded or processed.
I looked up the Alesis 150 -- it's a power amp to drive speakers, etc.
These units usually do not have a can stereo jack. You will have to plug your cans into your recorder's stereo can jack plug.
I noted that the unit had TRS plugs and 1/4 inch and RCA outs. So, I'm assuming it is merely a power unit for your speakers. Thus, I think you would run in a signal from your recorder so you can hear tracks and mixing sequence before burning to CDR or just sending to tape.
Since I use an integrated amplifier, I have a little different twist on my ins/outs. I run the stereo outs, RCA, from the back of my Yam 2816 into my integrated amp and then route the signal to either set of my speakers or to tape, etc.
I'd been using a quality stereo amp which of course had the headphone jack. I didn't even realize the RA150 would present a problem for monitoring with headphones.
My only alternative is a headphone mixer/amp between my PC and the RA150.
