don't like the dual connector cable on the 6xx
any other good phones in that price range with only one connector?
Nope. There's a reason why Sennheiser could still sell a 20 year old design made out of plastic for $300+.
Most headphones are just pretty bad unfortunately.
The only open alternatives, I guess, could be the Sony MA900 or Beyerdynamic DT880 if you like your treble hot. I can't think of anything else.
Also to the guy looking into the Grado GS1000, they're objectively garbage. They might sound great to some people subjectively but that doesn't change the fact that Grado puts no effort in R&D or improving their products.
At this point, I swear Grado knows their products aren't very good. All of their marketing seems to indicate that they believe people still think "Made in the US" means their product is of a higher quality than those from, say, China.