Yes, many interface all-in-one- inputs run even the separate line inputs through the preamp circuitry.  Some people claim it hurts the sound.  Ideally, you want separate inputs all the way to the bottom, but it cost more in items that are subject to strict cost structures.  But I've never had a problem w/ preamps after the line.  My Tascam UH-7000 is better going through the preamps than my TC konnekt line inputs.  I wouldn't worry about it, esp. at home, unless you are trying to sell time in your home studio.

HIGHLY SUGGEST THE FMR RNP
 
http://www.fmraudio.com/rnp.html
 
FOR THE UNDER $500 CATEGORY
 
 

You could get both the FMR and a Tascam U7000 for $874($475 +$399) and have 4 channels of "really nice" preamps, but maybe GC doesn't have the FMR stuff. Don't know about the One Q.
Michael
 

Regarding the ISA One, I've seen these versions at various sites:  ISA One, ISA One Analog, ISA One Digital.
 
Are there three models?

It's analog unless it has the optional digital conversion card.
 
Rocky

The ISA One is the analog.  Add a two channel AD and it is the ISA One Digital.  You can buy it w/ the AD, but most of the time it is just analog.
 
@

For  $399 usd you can add the 2 channel ADC card which fits into a slot on the back of the ISA One (and has a molex type connector to the circuit board, so it's fairly simple to add, though you will have to buy/make the proper 9 pin output cable). It allows you to select an AES or S/PDIF digital output, converting the analog preamp and DI (= 2channel) to a stereo digital out. You can also plug in 2 lines of anything else and run them through/out the convertor. Supposedly the conversion is very good("best in it's class"), though I've had a hard time finding out much about how it compares to other interfaces. Here's a link to a pic with the ADC card installed.
http://medias.audiofanzine.com/images/normal/focusrite-isa-one-digital-461841.jpg
   It's quite a handy preamp. I had been planning to buy a Cloudlifter Z, but those options (25db boost and variable impedance)are available (only 20db boost though)on the ISA One, so I don't need the Z, now. There's enough gain for an EV RE20 or ribbon, which is something to keep in mind when buying a preamp. 60db is good but for low output mics like those, 80db is much better.
   If, like me, you have an interface with a S/PDIF in/out, then the ISA One Digital is an even handier unit. I haven't bought the Digital Card yet, since I am about to upgrade my interface and don't know if I'll "end up" with S/PDIF or not. If I do, I definitely plan to add the card.
Michael
 
 

Well, I bought a Golden Age Project Pre-73 Preamp MKII (blemished), and a pair of AKG K240 Headphones.
 
I'm left with a couple of bucks on credit so I'll probably watch for a plugin on sale or guitar strings or...something:)
 
Thanks again for your input.  I'll post when I have a chance to test it out.

I know it's off topic but these kind of threads really get to me.
I envy you guys in the States for gear prices. In Australia we often end up paying nearly double for this type of equipment. There's the Austarlia tax (increased price because of where we are) and the exchange rate at present. When we had parity between our currencies I would often buy hardware from the U.S. pay shipping and still save 20% or more. Forget that now.

Okay.  The GAP Pre-73 MKII Preamp arrived yesterday.  It definitely adds color to my vocals.  I was able to find a sweet spot fairly quickly.  It can also accept a Comp and an EQ, so I can build a GAP channel strip later if I decide to.
 
I routed the Pre-73 to one of the inputs on my Quad-Capture leaving the SENS Control at '0'.  As far as I know, that bypasses the Quad-Capture's onboard preamp.  The next thing I'll try is using the Quad-Capture's Compressor in the chain.
 
I'm happy with the addition:) 
 
Thanks for the discussion.