A plug on the input is irrelavant and will only give you latancy while recording.

the signal has already been converted to digital by the time it gets to the plug
... so whether you have the plug now or at mix down ... it's all the same

IF you want compression before the conversion then you WILL need a physical comp post the Brick and pre the interface.
This is a fine idea BUT remember
once done ... it can not be un-done

Most of my track laying IS done with a Mic pre and a Comp before the interface.
Even the Synths go through the mic-pres and comps. post a DI box ofcourse

Take you time and look for a quality Compressor to go with your Brick.
To suit whatever you record the most ...

???
get a quality Mic first.

Kev wrote: A plug on the input is irrelavant and will only give you latancy while recording.

the signal has already been converted to digital by the time it gets to the plug
... so whether you have the plug now or at mix down ... it's all the same

IF you want compression before the conversion then you WILL need a physical comp post the Brick and pre the interface.
This is a fine idea BUT remember
once done ... it connot be un-done

Most of my track laying IS done with a Mic pre and a Comp before the interface.
Even the Synths go through the mic-pres and comps. post a DI box ofcourse

Take you time and look for a quality Compressor to go with your Brick.
To suit whatever you record the most ...

???
get a quality Mic first.

I see your point about compressing post conversion. I would prefer to never use a compressor at any point of the input stage but I have on occasion had musicians that left me little choice because they were so all over the place with their performance.

I agree with Kev. I do a lot of tracking with very, very subtle hardware compression after the mic pre on it's way to the soundcard. Sometimes, for effect and to tame extreme dynamics I'll cascade compressors. But very slight tube compression is a beautiful thing on vocals and acoustic guitars. It's extra special on back up vocals and electric bass. Just come straight out of your hardware compression into your soundcard.

You should try the quick mod on the 3630....it takes about 20 minutes and the sonic improvement is noticeable, mainly on ratios from 6:1 and up. It won't make a world class box out of it, but I use mine more than I ever did before. All it involves is cutting two jumper wires that tie the compressor to the gate circuitry. I believe it was posted here somewhere.....also in the April issue of TapeOp.

you will also find info at the LAB about the 3630
... a DIY forum with some hellpful people

It doesn't even have to be tube compression. An 1176 / 1178, LA3, LA4 all can be wonderful used subtlety or not. I routinely squish the snot out of stuff on the way to the recorder ... overheads (especially with a thick pre like the MPNVs) ... guitars in some situations ... vocals a lot and I never regret having done it at mix.

A lot of people don't like the LA4s but I think of them as sounding more like a VCA comp and I think that's what UREI was thinking with it. If you use them in the same aplications you would a DBX 160 in they can work very well. I do prefer the earlier Black face LA4s to the later silver ones.

yep
both work well on Vocals and Bass Guitars

the LA4 might be a little slower on the attack ... ?

The older LA4 that Kurt likes
could be the full transformered in and out and the output may have a little more grunt than the later ones.

Haven't seen enough LA4's to know for sure but the later ones could be closer to all silicon just as the later 1176's and the all silicon opamp based 1178.