One channel upgrade for ULN-2.
Since its release in 2002, the ULN-2 has enjoyed a legendary reputation for its pristine, wire-like gain, and has established itself as one of the best values in the professional audio industry. The ULN-2 posseses virtually every characteristic that is coveted in a Mic Preamp: exceptionally low noise at all gains, exceptionally high gain, excellent common mode and RFI rejection, incredibly flat frequency response, and ultra-low distortion. It simply increases the level of what you put into it without having to consider the nature of the source: Dynamic Mics, Phantom Powered Mics, Ribbon Mics, Instrument or line level signals are all handled with equal ease and quality.
So why change it?
The ULN-2 is an incredibly good Mic Pre, but sometimes you want something that isnt quite "so pristine". It is well known that a certain amount of low-order harmonic distortion has a way of adding depth and sheen to everything that passes through it which explains the high regard for to classic transformer coupled preamps.
Enter the Jensen Option
With the transformer option installed, the ULN-2 acquires that classic character. A few years ago, we fitted a prototype ULN-2 with a pair Jensen JT16-A's just for fun. We found that there were some very nice benefits to transformer coupling the input stage of the ULN-2. The Transformers impart a more "glossy", "smoothed" sound than the capacitively coupled ULN-2, which simply faithfully passes the source. Sonically, it's kind of like the difference between images shot on film and images shot in HD.
A second benefit is that the transformer completely electrically isolates the preamp from the source raising the common mode rejection above its already excellent performance, and providing a measure of confidence when dealing with the unknowns of location sound.