1578 for 6SN7GT

Can 6SN7GT tube be replaced with Russian 1578?
I have, in my Wyetech Opal. They work beautifully, a large improvement. Make sure they are genuine though. I bought mine from a gentleman named Paul Lindeman, who has been very reliable.

I have a pair running in my Counterpoint NP100. The real 1578 has metal base and round hole plates.
Thanks for sharing your experience.
The GT tubes have higher voltages then "plain" 6SN7 I believe.
I wonder if 1578 tube is suitable to replace 6sn7GT tube.

I have 3 pair of 1578 stamp .

I placed 1 pair in front of Cary SLP-98 and pair of GTB at back.

The result was very musical...too bad I sold my slp-98 and rest of my tube amps.

But now eyeeing for another SLp-98 to match my newly acquired vintage Threshold 4000amp.

Again it will work better than others 6sn7.