TRS Line Input Levels on Fast Track C-400

[Maris]

Hello,
I bought a used C-400 recently. I have discovered that the Mic/Line Combo Input has the same Input sensitivity regardless if one is using an XLR connector or TRS Jack connector. When I connect my professional Amek console's Balanced outputs by XLR or TRS connectors to the Mic/Line Inputs of C-400, the Interface and DAW Input meters show the same levels. From what I have read in the User manual I was expecting to have automatic switching between Mic and Line level sensitivity.
Look what is said in the User Manual:
These balanced/unbalanced analog audio inputs support
the following input levels:
• Mic (microphone) for XLR inputs
• Line (TRS) for line level signals on TRS or TS
inputs.
But that is not true- the Input sensitivity is THE SAME! Is this a problem? From a Pro point of view, yes. Line Input should always have a lower sensitivity than a Mic Input. A fixed Line Level input sensitivity is +4dBU (1.23V), while Mic Input is much more sensitive. The only way to overcome this is to use the Pad switch on C-400 and that is what I do. But that is not the right way. The Line Input shall have and automatic switching capability bypassing the high sensitive Mic Input chain. This is simply done with the use of XLR combo input's XLR/TRS detection.
I was expecting to read this in the User Manual, but sadly it does not have the unit's Specification at all...
If not this fact I am highly satisfied with the performance and the flexibility of the interface and it's Control panel.
So I am waiting for a reply to know if I am not wrong and maybe my unit is faulty and should have the automatic switching. My Yamaha Steinberg UR-22 does this function and performs it the way it should be- different sensitivity using different connectors.
Maris

[albee1952]

Its not a problem unless it sounds bad The difference is between a product that is really "pro"(the Amek console) and a product that is really "consumer"(anything made by M-Audio)

[Maris]

Happily M-Audio is probably one of the most popular of "consumer" Audio Interfaces. :)
In fact I already found the answer that almost all of the budget USB Audio Interfaces does not have True Line Level Inputs. The Line Inputs go through a resistor network to reduce the signal and match the impedance and then goes through the same Mic preamps as Mic Inputs. That sounds reasonable for me. What I like about C-400 is that it has the PAD switch for this to happen. That gives more flexibility to the user because can be used for Line Input as well as for high level Mic Input (drums).