I tried 19g in an 18g VST basket this morning. 38g yield. It was definitely a bit different. Nothing crazy drastic. I'll try lowering the temp a lot tomorrow.

Lowered my water temp today. Set to 208 on the PID. I don't have a way of measuring at the portafilter. Based on Auber's white paper, it should be below 200 though. I don't know. Again, no major changes. I just finished a bean that was giving me a slightly uneven extraction. On to a dry processed Ethiopian. I'll see how that goes.

try a smaller ratio. 1:1.5.

I know you said that you are getting nice looking extractions, but could you post a video of a bottomless extraction on the Silvia?

You also said that you are getting better extractions at work, I think the assumption here is that it is the same basket prep, grinder and beans. But, are you also single dosing frozen beans with a Sette 270 at work?

I'm just trying to narrow down all the possible factors. I'm more interested to see the bottomless extraction video as opposed to the work related questions, as it is hard to exactly duplicate two setups in two locations.

I'll try and video my morning shot.

As far as the work machine goes. Yes I used all of the same equipment and dosages.

Edit:
One of the main questions I've had that hasn't been touched on is, do machines have a flavor signature? All other things equal.

This is why we all started and then moved on from a Silvia.

Not perfect. But that was the second shot of a new bean that was only 2 days off roast.

Anyways. I turned the temp down to 206. This was a wild dry processed Ethiopian. I think the lower temp certainly tamed the harshness a bit.

Like you said the pull does look visually nice. There is nothing I can see from the bottomless extraction that would explain the harshness.

This is more of a question than a comment, but is it normal for your pump to pulse like that during the extraction? I have a much older Audrey, but I believe they use the same pump and I have never heard it pulse like that.

Another question I have is how often do you backflush with detergent and when was the last time you descaled? Either of these could account for harsh espresso.

As for your question regarding machine signatures. I don't have enough experience using that many different machines, but I think it is fair to say that each machine would have its own signature. The extraction process is so elaborate I don't see how two different machines would be able to produce the same tasting espresso, but I again I do not think I am that qualified to comment on that. Saying that, I do not think it is fair to say that the Silvia's signature is harsh tasting espresso.

With the Ethiopian DP, use a lower dose ( I use ~17g ) and grind finer for a slower flow.
I don't know about a flavor signature, but I think Silvia pulls ristrettos better than normales. 40 second shots are not unusual for me.
At least that's my experience.

For me, in the 17 years that I used my Silvia, whenever tastes were off, it turns out that she needed a good cleaning.

Cafiza, Dezcal, fresh water. Run the water reservoir through a hot dishwasher, with portafilters, etc. <<Shrug>>