Tascam US 4x4HR + Mixer

[hatschiii]

I have a Tascam US 4x4HR which is working very well. Now I need a mixer, too. Thinking about the Behringer X Air series for example to get not just mixing also deesser, limiter, compressor, etc.

The question now is that the mixer mostly have also a preamp included and I do not want to "destroy" my great sound quality from the 4x4HR preamp. How does a setup needs to be...

Mic >>> 4x4HR >>> mixer >>> Mac
Mic >>> mixer >>> 4x4HR >>> Mac
....?

What do I need to take care in the setup and what do I need to tace care of in buying the right mixer to not destroay the 4x4HR quality?

 

[hatschiii]

Can I use the Tascam as a mixer? right now there is one mic which goes through USB into the computer. I have now connected a sound source as line in (In 3) and want to give it, together with the computer sound, out on the phones 1/2 on the front where my speakers are connected to.

 

[SkywaveTDR]

The Tascam device is just a interface and it will do what it is suppose to and the mixer most have is in the computer. Cheap Chinese mixers as Mackie and others do not hold up long term and when damaged can not be fixed. They are called throw away mixers.
Teac made a mixer that is a line mixer called the Model one. It allows 8 inputs with gain and a Pan pot. So it is referred to a 8 to 2 mixer and also has a headphone amp built in. These are repairable and I have three or 4 of them here in my shop or on the bench. The function of the question above depends on if the device is a duplex or not. My Roland Tri Capture will do what you say but it does not have balanced inputs as it is for line level.