Do I need a DI box for recording my guitar?

A DI box (for guitar->mixer) has a high-impedance (500k or higher) jack input for guitars, often a jack output to then continue to your pedals and amp, and on the other side there is an XLR microphone level output to go to your mixer/interface microphone input.
 
If you use this type of DI box, you can play your guitar with your pedals running and your amp feeding back, but what you get on your recording is just your clean, direct guitar signal.
 
This allows you to "re-amp" your guitar afterwards. So in other words, it could be that as your song develops, you decide a crunchy distortion would have been better than a metal distortion. If you recorded clean, you can do this.
 
Amplifiers often have  line outs, as yours has. If your interface has a 1/4" jack input, then you do not need a DI box (unless you want to record the signal before any pedals you might have).
 
Your output has a cabinet simulator, but it is not clear whether the output is pre-preamp or post-preamp (typical guitar preamps have 2 channels - clean and distorted). This will also come into the decision you have to make.
 
Bottom line: If you have a jack in on your interface, no, you do not need a DI box.

What you have to be careful with is the input impedance of any 1/4" jack input. Not all jack inputs are designed to connect guitars direct to them at all unless they are labeled DI input.
 
For example a jack input might have a 10K input impedance and that is not so suitable for connecting guitars direct to. What will happen is the signal will work OK but you might find the very top end of the guitar sound will disappear. The jack inputs on my Yamaha digital mixer for example are 3K input impedance which is way too low for a guitar. It works fine but the top end really gets shaved off.
 
Check the specs of your interface and look up and see what any jack input impedances actually are. It will be in the specifications.
 
A DI box usually offers quite a high input impedance to the guitar in order to preserve all the signal level and frequency response. It is actually a great way to record guitar because it not only presents the right impedance to the guitar but it also connects to the Mic XLR input usually where there is also much more gain available for guitars with passive pickups etc..
 
A great way to record guitar also is to plug the guitar direct to the DI box first and record the clean dry signal from the XLR output. Use the jack output from the Di to feed pedals, effects and amps etc and also track that guitar from there. You might need two or more tracks to record the guitar part but having that super clean dry guitar signal available later on will come into its own once you start applying amp sims and processing etc over that dry sound.
 
 

The specs of the Profire instrument input is:
 

Inst. Inputs (Unbalanced) At Min Gain, No Pad

Frequency Response: +/- 0.2dB, 20Hz to 22kHz

Signal-to-Noise Ratio (min gain, no pad): 107dB (A-weighted)

Dynamic Range (min gain, no pad): 107dB (A-weighted)

THD+N (min gain, no pad): 0.0025% (-92dB), 1kHz, -1dBFS

Crosstalk: < -110dB @ 1kHz

Maximum Input level: from +14.5dBV @ min gain, no pad to -39dBV @ maxgain, no pad

Input Impedance: 1M Ohm unbalanced

Adjustable Gain: >53dB without padInput impedance is 1M Ohm. That is what I plug into when I use amp sims or when I have connected my amp's, or attenuator's, line out to.

You should be fine with what you are doing - you don't need a DI. Line out to line in. You are using the amplifier's preamp to get to line level. What would be better? If you are using a microphone a mic preamp is a good choice, if you're using a guitar a guitar preamp is a good choice. I have a number of different ways to interface my guitar to my computer, but for using amp modelers or effects I prefer using a guitar preamp. I have a guitar amp with an effects loop and I can switch my interface in and out of the loop. I also have a separate guitar preamp I occasionally use. A guitar preamp is designed for guitars and has the feel and response that most guitarists like. Micing an amp is nice, but it's problematic in a home studio. My 2 cents. 

Thank you for the good information! I don't have DI box (yet) but I have been looking at them on and off.
 
I generally do not like amp sims but playing my real amp and then applying an amp sim later might do the trick. I don't mind the way amp sims sound afterward. I just don't like hearing them while I am playing.
 
Do you have any DI recommendations as far as brands? Passive vs active?
 
Thanks

The main thing to check is that the DI box actually does habe an input impedance of 1MOhm or above. Also, connecting the guitar to the DI and the DI's 'direct output' to effects/amp often results in the guitar seeing the impedance of the DI box and the fx/amp as parallel resistances. This happens when the direct out on the DI is simply another jack socket wired directly to the input.

The result would be the guitar seeing e.g. 1MOhm at the DI plus a parallel 1MOhm from the amp. Which Ohm's Law tells us means the guitar is now seeing a 500Ohm load, which is a bit lower than ideal.

One way round this is to put a buffer with a 1MOhm+ input impedance between guitar and DI so the buffer is the first thing the guitar sees. Every Boss pedal (and quite a number of others) contains such a buffer, which is permanently active whether the pedal is on or off so long as it is receiving power. Most guitarists have at least one Boss pedal kicking around the place...

The whole DI before effects thing does falls flat on its face if you use certain pedals, such as Fuzz Faces and similar transistor fuzzes or some wahs because the guitar and pedal form a single circuit and if the pedal doesn't see the right range of impedances 'upstream' at the guitar then the pedal circuit doesn't operate as designed. Putting such pedals after a buffer, or even another effect that isn't true bypass or is switched on, also means they don't work properly. Typically fuzzes become much brighter, more distorted and refuse to clean up properly as the guitar volume and tone controls are adjusted.

The whole thing is a trial and error process. If you don't use the kind of pedals that are affected, don't worrry about it. Just run a buffer between guitar and DI.

I will look for an active DI but if I went passive, I could put it after my compressor. It has an input impedance of 1Meg Ohm and output of 2.2K Ohm. Or after my EQ; input 1M, output 510 Ohms.
 
Thanks again for the great advice!

I called Live Wire about their passive direct box today and asked if the input signal and output signal on the front of their box is exactly the same and they said yes. 
It seems someone was saying that the signal is degraded in some way but according to Live Wire, on their passive boxes, the signal coming out of the front is exactly what is going in. This output is not the XLR output on the box but the parallel out on the front.