Recording a guitar line from the amp?

Hi There, I have been using an M Audio Mobile Pre USB unit to feed my signal into my computer. Unfortunately I have found that it only records the direct guitar line. This is not ideal because I like the sound which my guitar produces through the actual guitar amp. Is it normal that the hardware which processes guitar signals to a computer only does it direct from the guitar? If there are exceptions, which are the best ones (ideally not expensive)? Trying to emulate my amp sound with VSTs isn't really fun or what I want to be doing. :/ :) Thanks

Buy a microphone and plug it into one of the mic channels. Going direct from the amp is possible, but it won't sound good.

Or if your amp has a headphone/line out, get the sound/FX you want and jack it straight into your audio input. I get great results with my Roland Microcube and an old Peavey amp.

Wait. Are you saying that you couldn't get sound from the headphone out on the amp so you ditched it altogether and then plugged the guitar straight into the interface? In that case, unless you're looking for a very particular type of clean sound, you're probably going to want a bit more than just a cab sim. Most guitar amps do some pretty drastic EQ even at moderate settings and most also introduce some amount of compression/overdrive/distortion even at cleaner settings. ReaEQ and ReaComp can get you there, but it's probably easier to find a decent amp simulator. Why didn't the phones out work? Well, what kind of cable did you use? A normal TS "instrument" cable really should have worked. A TRS cable probably won't though. Judders touched on why but didn't explain fully. The headphone out is TRS wired T>left headphone and R>right. Unless the amp has some stereo effects on it, this will pretty much be just exactly the same thing on both T and R so you hear the guitar right in the middle rather than only in one ear. The line input is also TRS, but is a "balanced" or more precisely a "differential" wiring. This means that it takes the difference of T and R as the signal. Now if T and R are exactly the same... 1 - 1 = 0

My guess is that your mobile interface has multiple inputs, microphone, instrument, or line level and you will need to select the appropriate track input options in Reaper. It will be helpful to know which amp you are recording since most tube amps do not have a headphone or speaker simulation out the only way to record them is with a microphone. It's not that hard to do. Unless you really love the sound of the amp I would invest in some guitar VST like Podfarm, Amplitube, Etc.

Thanks for the responses. This is all very interesting stuff and I'm learning as I go. The sound that I get in the headphones when I plug them straight into the amp is fairly decent to me in terms of what the amp is doing to the signal. The instrument cables I use are all TS. When I route the amp headphone out into the M audio Pre Usb instrument line the Reaper track immediately recognizes a signal which consistently reads at about -30 to -24db on the meter. This is regardless of what I am doing with the guitar or even whether it is plugged in or not. The amp itself is a super cheap little Ibanez IBZ10B. The Pre-Usb has 2 instrument line input sockets and 3 microphone inputs (one of which is like an earphone jack in size, so I wonder whether I could get a trs with a large plug at one end and earphone size jack at the other or maybe use an adapter on one end to make it fit and just use that input?). Thanks all