I use a tube pre with Ss amp. With my system it is very easy to evaluate any change and characteristics of input tube,rectifier tube, cables sprk and I/cs. That said I use the same input and output tube as your integrated and I have many different brands current and nos including jj 802s . I recommend based on your description that you try Siemens ecc82s a far different sound than the jjs and should get you closer to what you seek. Best.
