The primary issue @donavabdear appears to have is a noisy signal chain (noisy tube pre-amp + high gain amp will cause that). That is what you find out when you listen and research and do not jump to conclusions. @donavabdear , did you respond about how your subs were connected? That buzz sounded like what a single ended connection would suffer from.
The OP, @donavabdear lost some warmth, but gained detail and lost noise, and eliminated concern with tube life. @donavabdear , the first thing I would explore is a custom equalization curve. That seems well within the range of your Lyngdorf. I would suggest starting with a 1db boost from about 50Hz up to 350Hz. You can try bumping that 1db level up and down a 1/4db at at a time and play with the end points, but more so on the 350Hz, pushing it up a bit at a time. I am sure @kota1 can tell you why I picked those frequencies.