Manley Chinook with (very) low output MC ZYX?

@jbhiller you did end up replacing the opamps, right?  What did it do for your Chinook?  I think they are just plug-ins, so should be easy.  Did you use the single or dual op amps?  Would you do it again?

@soundermn 

Yes, I did do it.  I bought Burr Browns with some really great specs.  I wanted to first try them as opposed to some super custom ones due to expense.  The BBs were about $15 for two. 

I used dual op amps because that is what I think is in there to begin with.  I did the 2 in the amp stage, I didn't do the third one in the power section of the amp.  

I heard a mild improvement (not a big change) in further noise reduction.  There could be other changes that I just didn't take notice of because the surface noise (already quiet with the Chinook) improved a bit.  That was easily detectable because I know what noise to expect on certain records from playing them many times before.  

This wasn't a huge improvement but worthwhile and cost effective.  I'd be curious to try what Johnss recommended--the sparkos labs op amps.  But they aren't cheap.  

The one thing I can say about the Chinook is that it's going nowhere in my system.  I cannot imagine how much I'd have to spend to upgrade.  It's a wonderful preamp.  I'm really attached to it unlike other pieces of equipment. 

Correction--they BB's were $10 ea.  I got them here:

https://reverb.com/item/15240397-1pcs-burr-brown-opa2134pa-opa2134-dual-hifi-audio-opamp-new-ic

@soundermn 

Here is a cheaper solution that sparkos labs with strong specs.  Some say specs don't matter so much with op amps.  I have no idea and will let my ears be the judge. 

http://www.doukaudio.com/dual-discrete-op-amp-hifi-audio-preamp-operational-amplifier-opamp-replace-...

Very interesting!  Thank you for sharing your feedback!  I agree that it's staying with me too.  The only thing I would consider if I were upgrading is the Herron... but it's significantly more money, and I wonder how much better it really can be.