How to set a FXpreset ON at sampleset load?

Hi Cementimental,
You may have discovered a bug 
You can try with the fxpreset definition name starting with a an uppercase and rest lowercase: Isntecho in your example or completely lowercase.
Plse let me know the result !

Regarding the seemingly odd behaviour.

Presets change the values defined in this preset. In other words: they add up = override only the parameters specified in it.
If you have an Echo preset and a Modulate preset, loading them subsequently will give you a modulation with echo.
If you want a "clean" Modulate after using the echo, you have the option to either:

• set Echo parameters explicitely to default in the modulate preset
  
• load the Default preset first
  

The first option can be tedious, because this goes for all effects so you will have specify all these values explicitely if you want to be save.
And if you decide to set another sample set default you face serious work
So option 2 seems extra, but will save a lot of headaches in the long run.

Presets can be assigned to voices (multiple sounds within one sample set).
When switching voices, the voice will adapt to the fxpreset assigned to his sound (according to %fxpreset on his own definition line).
If there is no %fxpreset, it will fallback to the default.
If you want to keep the current effects values when switching to this voice, you need None.
Using fxpreset=default has the same effect as not specifying it (it is already default behaviour).

Now what is the default:
This is an addup of the box's fxpreset (defined in the configuration directory and has all presets to NO in the distribution) and the values defined in the %%fxpreset.

Some notes on your example below

• you have 1 voice (the saw)
  
• the %fxpreset and %velocity do nothing as they are not related to a sound definition
  
• If you need them: %midinote*.wav,%fxpreset=blah,%velocity=1
  will give better results. If %voice is not coded, it defaults to %voice=1
  

Since you code %%fxpreset as samples set default and (%)%velocity defaults to (%)%velolevs which has system default of 1, you don't need it in this case.

Hope this helps,
Hans