There's a review on TNT audio comparing the differences between the tube and SS rectified ST-70. Look it up because it addresses what you're asking directly. Hope that helps.
Regardless of either you own a vintage Dyna70 or the Panor Dyna70II, they are both classic amps that give you great value and great sound. It is an amp that anyone should own one, treasure and enjoy. Lately, Stereophile magazine has featured a new review of the Dyna70 duo in its recent issue. For your easy reference, please click the following:
"The new Dynaco Stereo 70 II is a nice, musical little amplifier, but a "giant-killer" it isn't; showdowns with the VTL 225s were not very favorable, in any possible dimension. What the new Dyna is is a very good reissue of a classic tube amp, with excellent build quality and pleasant, easy sonics. The new 70 isn't exactly the kilobuck best-buy I was looking for, but it's nice to see a bona fide audio classic reproduced with care and quality.
Conclusion In spite of my criticisms of the Panor/Dynaco, I should point out that this amp will kill most of the sub-$1000 mid-fi solid-state dreck out there; it's not the greatest amp for the money, but it is a well-designed tube amp, and that alone will ensure more long-term listening pleasure than a lot of the budget solid-state amps.
That said, I can't really recommend the Panor. You can find good-working vintage Stereo 70s on the used market for $200, and the new 70 II just doesn't offer a grand's worth of sonic improvement. There's enough excellent gear for a cool thou, both tube and solid-state, that the 70 II doesn't keep pace with. If this amp sold for $600, I'd say buy it even if you don't need it, but while the 70 II is a nice little amp, your $1000-$1100 can ultimately buy better sound. "
i tend to agree with this assessment having heard both models and comparing the sound with other true-blue vintage amps. however, for p20-25k i saw advertised for this, this is still a great value amp. but if you can afford to pay a little bit more, go for the classic/orig model. just my 2c...
The reviews of stereophile and absolute sound during this time were a bit at odds. The Absolute Sound review was in favor of the series II. I myself had the Series II and to this day hit myself in the head for selling it 12 years ago. This version was a small powerhouse with kick-ass response with modern speakers. It could play at generous levels with my old DQ-8 dalquist of that period. Very reliable as I know to this date.
Don't expect a really creamy sound from this version but a more modern sound, less colored presentation. A good tube preamp can easily change the character of this baby, as the sound follows the source.