Preamp help

I have a Consonance T1 pre that uses ecc82s. On the advice of others I had rolled tesla 802s in place and was an improvement over the jj82s. My question is can I safely use an ecc82 and ecc802 in series for each channel. The reason I ask is I had just upgraded my speakers and they are highly revealing. The 802s with this speaker has a somewhat recessed midrange but excellent imaging and clarity. The ecc82 has warmer and more forward mids but lesser imaging and clarity. I try one of each tube type in series for a short time to find it is the best sound I have from my pre to date. So if any one could advise on this Would be greatly appreciated Thanks