I'm sorry I didn't get back to this sooner - you might want to check if you can actually use the line in simultaneously with the XLR inputs. In fact, looking at the manual, I don't think there is a line-in, though I thought I saw one - I think it might only be the headphone/line-out jack.
You could, though, record a song into it (in real time) and then afterwards go back and play over it. If this is what you were planning on doing, then I think that is doable - you'll just need an adaptor to go from your mini-headphone jack (1/8"?) on the iPhone/CD player/etc. to two quarter inch plugs. I've recorded like that into mine and there shouldn't be a problem.
But if you wanted to play along as everything was recording, then unless you use the built-in mics to record your amp, then I don't think you can do it.
Also remember that recording the songs into the unit in real time is relatively time-consuming. You'll have to keep an eye on the unit so that you stop it at the end of the song so you don't have a huge file with empty space at the end.
Re: listening back: it does have a mono speaker that you can listen on, or you can listen on headphones (or plug it into a speaker system). You can just leave the files on the H4n and play them from there - I do that with stuff I record at rehearsal - listen to the tracks and only import what I want to into my computer.
I hope this helps! Feel free to contact me if you want to talk about it, or ask here is fine too. By the way, the manual is here:
https://www.zoom-na.com/sites/default/files/products/downloads/pdfs/Zoom_H4nPro_English.pdf[/quote]
Yeah I mistook the headphone jack for a line-in.
Im also realizing I might be a luddite after all...I ordered the Soundcraft 8 channel mixer from amazon and it arrived last night. I played around with it for a little last night after downloading Reaper and than spent a few hours this morning with it and ended up getting pretty frustrated with it.
I plugged the USB cable into my MacBook pro, and I used the RCA jacks on the soundcraft as an input for audio from my iPhone, channel 1 had the DI from my demeter going into it...and for playback/monitoring I was using a bose revolve plus bluetooth speaker. audio from the phone played back fine, however there was some weird latency issue with the bass. I'd pluck the string and it would come out of the bluetooth speaker a second later than it registered on the reaper software or from what I'd hear from my amp. Playing back the recordings I made there seemed to also be some lag between what was coming off the audio from the iPhone and what i was playing on bass. At first I thought my timing was just off with whatever track I was using but I verified it with a metronome and the lag seemed reproducible.
Next I tried just using headphones for monitoring and I just simply could not get any sound out of the headphone jack of the mixer. There was nothing but some sort of electronic noise coming from somewhere.
Frankly dealing with the software and the mess of cables is just far more effort than I want to put into this...All I want to do is critique the bass lines I'm coming up with against existing recordings or apps like irealpro of drum genie. I think this mixer is going back to amazon and I'll just stick with the old Sony PCMD50 i have..Not perfect but probably good enough for my purposes.