If you don't have one, a Pro-Ject Speed Box (or Music Hall's version) is a very good upgrade in general. It's not just a convenient 33/45 rpm changer.
I use on on my Pro-Ject 1Xpression and have heard them on other Pro-Ject's and Music Halls. I haven't heard it on the MMF 5.1 specifically, but the all share Pro-Ject motors, and the 5.1's motor may very well be the same as my Xpression's. The improvements are across the board; there's not improvement in one area at the expense of another. It's very hard to find that in this hobby.
The Speed Box 2 is about $150, so it's not a major expense. Places like Music Direct have a 30 trial period, so there's almost no risk. Haven't heard the Speed Box SE to be able to say if it's worth the extra cost.
I use on on my Pro-Ject 1Xpression and have heard them on other Pro-Ject's and Music Halls. I haven't heard it on the MMF 5.1 specifically, but the all share Pro-Ject motors, and the 5.1's motor may very well be the same as my Xpression's. The improvements are across the board; there's not improvement in one area at the expense of another. It's very hard to find that in this hobby.
The Speed Box 2 is about $150, so it's not a major expense. Places like Music Direct have a 30 trial period, so there's almost no risk. Haven't heard the Speed Box SE to be able to say if it's worth the extra cost.