Rogue Audio Dark Upgrade.

I have run Rogue Monoblocks for over 20 years starting with the 120s that were upgraded to 150s. That jump was massive. Better amp in all areas. They also ran much cooler as the 120s were mini space heaters.

I then sold the 150s and bought a pair of 180 darks. They have a bit more "darkness" and top end detail, but the difference between the 150s and 180 darks was very subtle. The most interesting thing is to my ear, they need to warm up at least an hour before they really get going. After that hour...they are a steal at the price point.

Also want to add that Rogue has splendid customer service. Usually Mark (the owner) responds personally. Just my 2 cents 

Thanks guys for some very informative information plus tube suggestions.  I have several 12au7 to try but will need to search for 12AX7 or 5751 that don't break the bank.  Or wait a little while until prices return to normal.  Hopefully.  This is definitely where I'll start before any other upgrades.  

@charcoalchuck agreed that Rogue is a steal at the price point.  I've had some really nice tube amps and the ST-100 rates extremely high.  Not sure its at Audio Research Ref level but pretty close IMO. Referring to older Refs and not the newest series. 

@mulveling 

thanks for your insight on the dark upgrade.  i am on the fence about a stereo 100 basic or dark.