Before I order this amp, I have little questions to be clarified.
 
My current setup:
 
MHDT Havana DAC --> WooAudio GES --(LoopOut)--> Wooaudio 2
 
Wooaudio2 does not have any LoopOut. So if I get Concerto hook up to Havana DAC, what are my options?
 
My best guess is to get RCA splitters on Havana DAC output. If so, will I be able to run all 3 amps at once? or do I need to choose either one at a time?
(I currently use GES and Woo2 at once with no problem. but between Concerto and either Woos...not so sure.. because of the splitter)
 
The main reason for purchasing Corda Concerto is to have SS amp with high current (more energy) to low impedance cans like Grados or Denon.
WooAudio2 for higher impedance cans like HDxxx or ByerXXX. Am I targeting right?
 
Do you see any bottleneck on my setup? I wonder if I am investing too much on amps while Havana is a mid-range DAC... (I love Havana thou!!)
 

1) I have a query of my own. Why loop and use 2 amps together?
2) Assuming the Havana has two sets of RCA outs, you can use 2 amps along with it. But why? Unless you plan on listening to two headphones a lot. Seems like a waste of desk space to me.
3) The Grados pair well with tube amps it seems. Ask me I'm searching for a good tube amp to drive the Grados, unfortunately I also have a D7000 to keep happy, and that doesn't seem to like tubes. But with grados, look at tubes, might be you want to get a WA6SE, and sell off the WA2. I've heard the WA6SE is more lively, faster, while the WA2 is a little darker and warmer. However, I've never owned either, so please don't take my word as gospel.
4) It seems the concerto does well with the T1s. Might be you want to get the Concerto and later, sell of the WA2 and get a WA6SE stock. That way, you'll have one great tube amp, and one very good SS amp.
5) I don't think the Havana is a bottle neck ATM.
 

Yes thats one of the reasons I went with the Woo6se, equally good with low and high impedance phones. Love it