Transformer Woes (Loading?)

I switched input transformers on my One-Bottles to Beyer TR/BV 351 015 006, and I have since thought that they sounded REALLY muffled. Here's the RMAA...

http://www.twin-x.com/groupdiy/thumbnails.php?album=143

The 100k/100pF zobel used as an example in the data sheet was tested as well as zobel-free. The DI input looked dandy. One of my racked PM-1000s was thrown in for comparison's sake.

I also ran a test with 440k across the secondary (no difference) and one using a direct box in between my soundcard and the preamp (same except for the low end bump being gone).

Should they really be 10dB down at 15k?

First things first: are you testing it from the proper source impedance? If not, the test result is meaningless.

Also, what's the signal level? How about the load impedance on the output?

These things should always be specified.

To answer your other question: no, the frequency response shouldn't look like that.

Oops. Sorry.

The output impedance of my soundcard is 100ohms. That went through an inline pad (same as the one on the One-Bottle schematic). The pad on the preamp was also engaged. Would the source impedance then be 220ohms?

The signal level was +4dBu.

The output transformer (Edcor WSM10k/600) drove a 32k input.

Thanks Dave!