Can tube preamps be as 'detailed' sounding as ss?

Admission: I didn't, and still don't, know what the acronym 'IOW' means...

About the amp thing, I play electric guitar, which as you know is often intentionally distorted, either via amp overdrive or by a fuzzbox, and think I'd have a pretty good sense of it if heavily distorted sound were actually perceived as being louder than undistorted sound measuring 30dB higher in level. I understand that the ear/brain is supposed to increasingly identify and object to harmonic distortion with increasing order. However, I don't think it's universally true that SS gear produces more of this content, although it may be true that tube gear generally produces more low-order content which helps mask it. (Although what you're alleging sounds as if it might have more to do with TIM than THD.) You are right though, I'm not aware that the ear/brain uses harmonic content to help determine loudness -- do you have a citation on this?

IOW means 'in other words'.

The 'citation' I've been referring to is the study by General Electric that was done back in the 1960s. In it, they found that people will tolerate quite a bit of even-ordered harmonics added (up to 40%), but were not tolerent at all of odd orders, objecting to vanishingly small levels. The study showed that the human ear uses odd ordered harmonics as the primary means for determing loudness.

What this means for audio design is that designing with an eye to remove this harmonic content (+9th odd orders) will result in a more relaxed presentation.

If you want to see how this works in the tubes vs transistor thing, all you would have to do is run a sine wave into a preamp, run it up to clipping and view the output with a scope- the tube unit will have a rounded waveform at clipping, the transistor unit will look on a scope like somebody cut off the top of the waveform with a scissors. This 'cut off' area is a place where odd ordered harmonics abound.

Semiconductors, even FETs, by their very nature tend to generate these harmonics more than tubes, even if not being overloaded. It is something that comes with the territory in things solid state.

My active solid state preamps (H2O Fire) couldn't be more clear, with no discernible foreign harmonics whatsoever. What they are, I don't know. The builder says, unconventional. Whatever, it works.

Atmasphere: Most tubes go into "soft clipping" ( rounded edges ) because they don't have the necessary speed / bandwidth to reproduce the sharp edges that make up a heavily clipped sine wave aka a square wave. Then again, i'm not telling you anything that you don't already know, so this is really for everyone else reading this thread : )

Other than that, i've always been a proponent of having "MEGA" overhead in system capacity. I learned a LONG time ago that it is not sheer spl's that make things sound "loud" and / or "aggressive", but distortion. By using high powered amps that are never pushed, and speakers that aren't easily driven into compression, one can listen at astonishingly high spl's with little to no fatigue. Not only that, but it doesn't sound nearly as loud as it really is. That's because the system is free of distortion, which is what adds the apparent volume that brings both fatigue and ear strain with it.

As far as Muralman's comments go, most good quality switching amps can sound quite clean even when spl's are roaring. This has to do with their reduced duty cycle, which minimizes thermal stress. When it comes to SS amps, the faster that you can dissipate heat, the better off you are. Both sonically and in terms of product lifespan. Sean
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Thanks Atmasphere. I can well believe that it's a murky business trying to discern volume differences using pure sine waves, and also that incipient high-order distortion can cause listener fatigue. But I always regard at arm's length claims which seem to equate A) music signals with sine waves, or B) amp behavior below clipping with amp behavior around clipping (particularly when it comes to preamps, which shouldn't even get anywhere near approaching clipping).

Speaking of preamp distortion, the new Stereophile has THD measurements from JA on the Mac C1000 (figs. 5-6 and 9-10), which for practical purposes seem to indicate all but indistinguishable (not to mention negligible) distortion behavior between the unit's tubed and solid-state options, at least within the limits of the test conditions.