I would have to say that this setup is pretty bomb.  I put two 627's in slots 8 and 10 with one LM4562's in slots 9 and 10.  The sound itself is amazing.  Never had I heard so much detail and musical separation in my life.  I honestly was rediscovering old music and noticing all the little nuances that I didnt know were present.  The music itself sounds slower, but the vocals are in front of it and there's more depth.  Bass has a good amount of impact and is nicely extended.-

Hi Taisho,
 
I know that this post is about 8 months old but did you mean to say that you put FOUR 627s via an adaptor in slots 8 and 10 (2 in each respectively) and TWO LM4562s in slots 9 and 11 (1 in each respectively)?
 
Thanks in advance.

Curious about this myself as I am looking to do this upgrade.
 
Found this thread about it. http://www.head-fi.org/t/540541/good-opamp-for-a-ht-omega-claro-halo-using-grados
 
Looks like you do indeed need 2 627's for 8 or 10 since they are mono. And you do need to use an adapter such as this. http://cgi.ebay.com/2x-DIP-DIP-Dual-Mono-Opamp-PCB-Adapter-OPA627BP-/350414669117?pt=LH_DefaultDomain_0&hash=item519657853d
 
I would love to hear some confirmation though since I am also learning.

There are all kinds of great opamps out there.  Do some reading on what units people are testing out.  There is an ppamp thread in the DIY section, which should be able to answer any questions you have. 

Quote:

warofgears3 said:

Hi Taisho,
 
I know that this post is about 8 months old but did you mean to say that you put FOUR 627s via an adaptor in slots 8 and 10 (2 in each respectively) and TWO LM4562s in slots 9 and 11 (1 in each respectively)?
 
Thanks in advance.

Click to expand...

Yes, you are correct. Sorry, I don't check head-fi that frequently anymore, but that setup works pretty well.