From what I’ve seen they (12AX7) seem to be the input tube for this Line Magnetic 219ia amp.
If you have plenty of gain on the volume, you can try different 12A*7’s.
The AX7 has the highest gain, but to me for an input tube on an amp, it’s a bit bright, good for phono stage inputs though.
The 12AU7 has the lowest gain, and will sound more mellow.
The 12AY7 is my favourite from the 12A** series, for amp input tubes, who’s gain is between the AU and AX.
Cheers George
If you have plenty of gain on the volume, you can try different 12A*7’s.
The AX7 has the highest gain, but to me for an input tube on an amp, it’s a bit bright, good for phono stage inputs though.
The 12AU7 has the lowest gain, and will sound more mellow.
The 12AY7 is my favourite from the 12A** series, for amp input tubes, who’s gain is between the AU and AX.
Cheers George