Tube amplifiers and interstage transformers

I am sure that one can find a lot of people in either camps -- those that hate "iron" (limited bandwidth, phase shifts, etc) and those that hate caps. I have not personally experimented with design, so I cannot speak to theoretical advantages. It just happens to be the case that the amps I like are in the "lot of iron" camp. I have a pair of Audionote (uk) Kageki amps. These are interstage coupled.

I also own a pushpull amp based on an old Western Electric 133-A design, and a linestage that is also based on a Western Electric design. The linestage has input transformers and output transformers (no caps other than in the power supply) and the amp has input transformers, and again, no caps other than in the power supply.

My phonostage has a step up transformer in lieu of an active gain stage for low output moving coils.

Have to agree with Larryi, definitely two opposing camps.In theory the
limited bandwidth argument against transformer use makes some sense,
until you put theory aside and actually listen.In my experience the best
sounding amps and preamps more often than not take the high quality iron
route. Tube amps with interstage transformers sould exceedingly natural
and realistic compared to other topologies.They are utterly transparent and
have superb tone and body. My 2 cents worth.One of the
very best power amps I've ever heard, the Absolare Passion PSET 845
tube has the IT and is stunning! Both my amp and preamp use them and
sound
wonderful to me.
Regards,

Out of curiosity, it appears as though the interstage tranny is a big help with impedance matching. What I don't understand is why bandwidth is limited within the realm of human hearing i.e,why they even have this effect. Seems like you should get cleaner more powerful signal from the stage that needs to be matched to the next stage when impedance is better matched.

Mechans,
In reality you do get the advantages you describe despite what opponents
of the IT may claim.As alan pointed out, Many of the very custom and cost
no object designs use them .For good reason, when implemented
appropriately they produce excellent sound. I do recognize that other
designs can provide excellent sound also.Interstage transformers are a
time tested and proven pathway for superb sonic results.
Regards,

I agree with Charles1dad and Larryi, most of the best tube amplifiers I have heard have interstage transformers. And like I said before, some of the highly regarded ones also have interstage transformers.

It looks like if you want your interstage transformer not to reduce the bandwidth or affect negatively the sound you need to buy a really good one.

Still, a lot of amplifier designers and people with high knowledge of audio will go for no interstage transformer approach.

The issue is that besides the impedance matching Interstage transformers bring a kind of naturalness to the sound, question would be how?

I have a 45 SET amp built by Bob Danielak and it sounds amazing. It does not have interstage transformers at all.

Some of the Audio Note kits have interstage transformers and people really talk great things about them.