Marsh P2000T hybrid preamp....Should I modify??

I have done simple modifications on this preamp myself. First, change stock feet to "superspike" type or equivalent. Take a 1" by 0.25" aluminum bar and bond it with marine epoxy to the underside of the top cover in the long direction. Then buy a pair of HAL-O damping instruments from Herbie's Audio Labs and put them on a pair of Tung-Sol D-getter NOS 5687, which you can get for under $100 per dozen on Ebay. Finally, put on a VPI Magic Brick at the rear middle of the top cover.

Voila - no more microphonics. The preamp is silent up to -10db attenuation. I have installed a -60 to - 10 db switched attenuator and silver contact selector switches, which I highly recommend. Really good ones are available from www.goldpt.com. Apparently the guy will give you custom 24-step attenuator if you tell him the range you want.

The service you cite looks good and comprehensive, but should include the attenuator for best performance. I consider this Marsh preamp the best line circuit available today. It is made to a price point and can be improved with better parts.

I have ordered a pair of mono 100K series attenuators from Gold Point. I will report on the effect of these instead of the Marsh's balance and volume dual Alps pots.

Well, polarity is a complex issue. Some people are sensitive to it, some are not. In a well recorded material, where relative polarity of all tracks is maintained, inverted polarity at playback is heard as lack of ambiance and pace in the mid-bass.

However, most material is not recorded in such a fashion. Often different tracks have different polarity and final polarity of the master is either "in-phase" or "out-of-phase" with the original event.

Therefore, since polarity is essentially random on most recorded material, it is not really necessary to maintain it on playback.

However, for those rare records and CDs that are recorded in constant and correct polarity it is nice to have it right on playback.

So, I do hook my speakers backwards, as per Marsh's manual. Since their manual is the first manual for a tube product that never mentions the word "tube" it is remarkable that they decided to include the relatively exotic topic of polarity into it.

I wrote to Marsh, that since their manual excludes instructions on how to change the tubes entirely, they should expect customers to start returning them in about a year, complaining of lack of air and drive.

I can report good results from bypassing the main coupling caps with REL TFT 0.1uf 400v units. The sound has gain more air and presence and improved in the areas of pace and drive.

However, the soldering required is a bit tricky, as the leads from the bypass cap can't touch the ground plane of the PWB and the main caps leads are only about 1/8" above it. Can be done - just need to be careful.

Well, how does the darned thing sound after the upgrade ? I am installing Gold Point attenuators shortly and plan to add at least some of the commercial mods via homemade tinkering...