A no nonsense industrial design built around the type 85 tube which is much larger than the 12 series most preamps use and it provides a substantial soundstage Kara, the designer, provided a full compliment of replacement tubes as I had purchased the unit used and got me up and running. She also suggested a Sylvania 593 triple rectifier 3 mica tube that definitely outshone her own stock tube. 4 sets of RCA inputs, 2 sets of RCA outputs so one can run a subwoofer. 32 stop volume control of her choosing. This piece replaced a Manley Neo-Classic preamp with very upgraded Takatsuki 300B tubes. The Mercury seemed to outperform the Manley as far as soundstage and dynamics.

The only perceived weakness could be its very industrial design. She is no architectural beauty, no shiny bobble. This company is no longer building and selling as Kara has stepped away from the business.