What's A Good Upgrade From A Manley Steelhead?

Using what with a SUT?  The Steelhead has three pairs of phono inputs.  Two are for MC cartridges, and one is for MM.  You can choose up to 65db of phono gain.  So there would be no need for a SUT with most LOMC cartridges down to about 0.2mV output. (I actually used mine successfully with an AT ART7, which outputs only 0.12mV, but that is probably owing to the fact that the Beveridge amplifiers are "sensitive".)  Right now I am using it with Koetsu Urushi, and the attenuator is not even at its midpoint for very high SPLs in my large basement room.  But maybe you did not refer to the Steelhead.

Van Den Hul Grail - very quiet current mode, I have the SB model

Esoteric E-02 - compares well to top phono stages-  seems to be a sonic bargain 

@marantz8  Not presently. I ran an Audio Tekne MC 6310 (0.1mv) and used an Audio Tekne SUT for a while, but it actually worked better without the SUT.

I have Chinook SE, not a Steelhead, with a Bob's Devices Sky 20 SUT and a Hana Umami Red cartridge. Adding the SUT was an improvement.  I'm very happy with the results.

I am not one for cliche's but you would have to wrest the Steelhead out of my cold dead hands for me to give it up. It is seductive and rapturous when given a decent set of grooves. As I type this I am listening to the remastered version of Kate Bush's "Hounds of Love" with a Reed 3P arm and Lyra Etna Lamda. Drive is a highly modded Garrard 301. I don't for a minute disbelieve that the CH Precision, various Allnic units and more deliver something that can be called "better". But if your Steelhead is holding you back than you have Fifth World problems-assuming your TT is set up optimally and assuming you have heard it with good pressings. My Steelhead is dead quiet, dead reliable, and so satisfying (to me) from every perspective. After 2000 hours I did re-tube it with tubes supplied by Manley Labs which were very reasonably priced.