One way to do this is by brewing a series of SMaSH beers (Single malt and single hop) One base grain and one hop. Usually these come out as pale ales or Ipas. You could do as many variations of this as you wanted. You could also do a five gallon batch of this, and split it into 2 batches (or 5 i gallon batches) and ferment with different yeast.
Another option would be to use the same amount of base malt say 6-8 pounds and add a pound of a crystal to the recipe and make a series of beers with different combos as well.
Just don't change too many variables at one time, or you will not be able to discern what variable is doing what.
this is not limited to ALL-GRAIN BREWERS ONLY
you can SMaSH with extracts as well....
Some liquid extracts, expecially the lightest lovibond ones are SINGLE MALT as well.
Northern Brewer #20053 NB Organic Light Malt Syrup...Or even using XLT DME and a single hop would be an extract alternative.
Or a base extract + a couple ounces of steeping grain and a single hop. This isn't quite a smash...but you can use that to get an idea of how a steeping grain flavors a base of extract.
But there all 100% single malt (non blended/non hopped) Liquid extracts as well.
William's Brewing even offers Marris Otter LME. MARIS OTTER EXTRACT 8 LBS @ Williams Brewing
Briess offers an all Pilsner Malt Extract Pilsner Malt Extract | MoreBeer
So you too can play the SMaSHing game, it's not the sole propriety of the world of AG.
When I posted this info before someone remarked that some of these extracts aren't pure single grain ones, that they actually are a blend. Though there are organic 100% single malt extracts available but I'm not sure where.
No matter if it is blended or not, the concept is the same. A consistent base malt extract with a consistent single hop. As long as the ingredients are the same age, and preferably from the same batch, an extract SMaSH experiment would be educational.
It's a great way for everyone to get more control of their process, AND to get a feeling for how ingredients work with each other.
When I posted the links to the single malt extracts, a couple brewers told me they were going to do the extract smash...I haven't heard how it went.
Just take lots of notes.