Sounds like there's a problem with the lig... at certain points, the Durga sounds squeaky.
I have had many Wanne metal pieces... I've always hated the stock ligature, since it tends to bend the sides of the table.
If you try the Durga 4 with the FL Ultimate (or any fitting Rovner), you'll notice mayor improvements on the response (and overall control).
I've had at least two JJ DV in #7* tip opening... it's quite bright and thick.
On DV's my favoutite tip opening is the #8*... and sounds much brighter then the DV #7* (I still have one, #8*).