no line out - can I use speaker out

Guitarist likes the sound he gets out of his amp - so I looked for a line out to go into my presonus which then goes into Sonar 8.5
There is a "speaker out" but when I use this I don;t seem to be able to change the recording level.  I guess I could always mike the amp - but would rather go straight into the board.  Am I missing something?
Thanks
 

Get a direct box that will allow you to take signal straight from the guitar and send it to your presonus interface.

BJ may have a point that you may have damaged you interface input. If you haven't, consider yourself lucky and stop that practice. The output of a guitar amp is made for one thing: a speaker. It's more complicated than that, ( it's kind of a golden rule to follow in the studio and live sound) and this is a very simple explanation of what not to do.

Grem  A DI box is only needed to change the impedance of the signal and mostly this is only needed when working on stage to send a dry signal to the FOH,  Acoustic guitar or bass, most all sound people mike an amp.
There is absolutely no need for a DI box in a studio where your sitting 5'-12'  from your interface. 
You simply plug in directly using the interfaces instrument jacks. 
 
There is no substitute for a good guitar, a good amp and miking the amp. The speaker is a big part of the sound. Amp sims are OK for people who are after a processed tone.
Most of us are used to the response and tone we get when using a good , usually tube, amp. You will play better. 
The line out on most guitar amps is often not even after the pre amp so totally pointless. 
But there are many who like the processed type sound so there's a case for that person using a pedal board and /or going directly into the interface line or instrument  jack. 
 
That was real dumb to use a speaker jack, your bloody lucky your interface is still alive! Please take the time to learn the basics of audio before you touch any more wires....

Cactus, you are correct in you referencing some of the different uses of a DI. But they are often used in recording studios when even a few feet from recording console.

Example:
http://www.tech21nyc.com/..ucts/sansamp/index.html

Many recordings you have heard used a similar device. To say a DI box is not need isn't really justified.

As a guitar player what I would like, if recording through an amp with no line out, is to get a direct signal to the recording board/mixer/interface.

Not confused. There are other DI boxes as I'm sure you know.

Have a good day.