I have a tascam dr-40. I rate it. Not sure if the h4n supports line in on the TRS inputs, but for the tascam I have TS -> RCA adapters and use the dr-40 for recording DJ sets, as well as being able to use it for mic in, also the built in mics for field recordings. Preamps aren't that awesome on either device, but still good for portables. you can also get an AC adapter for the dr-40 and run it off power if for example you wanted to record a long time (e.g. open -> close for a club night).