Help ...... excesssssssive sssssssssssssssssssss

I suspect the problem is your extremely unusual choice of amp and speakers.

First Watt F1 is a current power amplifier...it will attempt to drive your speakers with a current that is independent of impedance load.

Your speakers only have one driver...it is unlikely that the impedance curve is anywhere near flat ....even it might be an easy or efficient load to drive.

I don't know the impedance characteristics of your speakers but most speakers are such that they tend to be of higher impedance at higher frequencies and usually high around the resonance point of the driver (which for 4 inch is probably some where in the lower mid range or bass).

The end result of this combination is that you will accentuate the speaker response according to the impedance curve...i.e. emphasize the resonance frequency and accentuate the treble (if your speaker behaves as most speakers do) => you will get significant bass and treble response boost and this is why you hear so much sibilance

Current amplifiers are rarely used in audio applications for this very reason....they need to be carefully matched to a speaker with a flat impedance curve.

First off let me say in my humble opinion you have a fantastic system.I don't believe the problem stems from one thing over the next.If you are putting together a system then you have to look at the system as the source of the problem.You have been given a number of great responses of which i would look into trying each one,but do it one at a time and listen for the changes that come about as you go on.Good luck

Speakers...
Hornshoppe are those very little very nice back horn loaded full range drivers, Fostex right?
I can bet your problem is the Whizzer...

I used to have a kinda Bazzilla speaker with DX3Lowthers on open bafle, I had to really fight ot get the SSSing down.
First point: silver cables give cleaner highs.
Second point. Add a super-tweeter, I started with a Fostex FT17H and then upgraded to a Beyma CP21-f
I have the Martin TL boxes with Fostex FE 207E drivers on a second system and its pretty nice, I got those to get better bass than I was getting with the the Lowthers, transparency is better with lowthers though.

I think you have a great system, I dont mean to be rude but I think its time to upgrade your speakers, I got Cabbase Loudspeakers after a lot of fiddling around with Full range drivers and they beat every Fullranger I heard in any aspect, more transparent more dynamic more coherent and of course better bass and better highs.
They say lowthers have a lot of bite, my Cabasse have more bite than my lowthers, I had to tame them good and they are sooo sweet now!!

PS- Not connected to Cabasse....

All the Best

Dear Socoaste: Shadorne is right on target: speaker/amplifier synergy, there is a severe mismatch between them because each other impedances.

If you like your speakers then you have to change the amplifier or the speakers if you like the amp.

It is a very hard task to match your amp to any speaker. I have a lot of respect for N. Pass but I don't know what he was thinking when put on sale those amps.

Btw, ask to N. Pass what to do about. His amp is the trouble.

Regards and enjoy the music.
Raul.

First off thanks for the ideas everyone....

The problem is showing up on digital And vinyl, but is
worse on vinyl playback.

speakers reflections......I don't think so, I have diffusers & studio foam to tame that area.

does not matter if at start of record or at last track.

speaker to amp mismatch....well, I know a few persons that
have the F-1/Hornshoppe combo & they are quite happy with it. the drivers I have are the Fostex 4" FE126E which are the latest driver that Ed (Hornshoppe) uses in the Horns.
most guys (including Me) are using accoustic stuffing in the horn throat
to damp the driver, since there is practically no damping factor with the F-1.

later this evening when it is cooler, I'll turn on the F-1
and maybe do a little more experimenting, (I don't have A/C
& that F-1 puts out some serious heat!).

-socoaste