Awhile back, maybe a couple of years ago, Andy Santana hipped me to a pedal that he was endorsing, the Lone Wolf Harp Tone+. I ran across a used one at good price on the Internet, so I bought it.
I decided to try it at the Mojo Lounge jam with a Harpgear Double Trouble and a Shure 520DX with the standard dynamic element with the following results.
I found that the pedal added quite a bit to the bottom end. It projected well for an 18 watt amp with a pair of 8" speakers. The addition to the bottom end was much more obvious when playing higher pitched harmonicas.
A few weeks later at the same place, I tried the Shure 520DX, Harp Tone+ and a Meteor Mini Meat joining Steve Freund performing the title track from his CD release entitled "Lonesome Flight".
I had some additional time with that combo to record this solo piece. (A Shure 520DX was plugged into the Harp Tone+ and into the Meat channel of the Meteor Mini Meat (2x8, 1x10 w/ 5881's). The volume was cranked to 6, tone and presence knobs set at about 7 on the amp. The Harp Tone+ was set as follows: Bass at 5 o'clock (full), Treble at noon, Volume at about 9 o'clock which was set at the brink of feedback. I stuck a Zoom H2 behind the amp.)
I also tried the Shure 520DX, Harp Tone+ with a solid state Peavey Bandit 65. I was very surprised with the results. It was quite loud and toneful. I didn't get much of an opportunity to dial it in, but it sounded very usable. It was usable enough that I wanted to mess with the combination some more.
If you don't want to spend a bunch of money on a vintage microphone, the Lone Wolf Harp Tone+ will nicely complement any of the contemporary harp mics like the Shure 520DX, Superlux D112 or the Astatic JT30-RH.