Many years ago, most, but not all of the Spanish Makers that existed at the time combined to for a National Spanish gun company. It did not work and most of the companies dissolved. Several good gunmakers were destroyed in the process. A few, like AYA emerged from the rubble and rebuilt their reputation.
By the late 1970s and early 1980s Spain's economy (along with the economies of most of the rest of the western nations) was circling the drain. The Spanish shotgun makers were especially hard hit, with less and less demand for their guns. When Victor Sarasqueta (arguably the largest of the shotgun makers) had to close its doors the rest of the gun makers were justifiably frightened.
At this time the Spanish government intervened to the extent of guaranteeing the financing to collectivize the shotgun makers into one large company/cooperative and modernize the means of production (including CNC milling). This company/cooperative was named Desarrollo de Industrias Armeras (acronym: DIARM). Some of the gun makers joined DIARM, and some did not. The names of some of the better known companies that join include Aguirre y Aranzabal (AYA), Gaspar Arizaga, Francisco Sarriugarte, Martin Ugarteburu, Gregorio San Martin, and Miguel Larranaga.
DIARM failed for a number of reasons, and all the small gun making companies that went out of business to join DIARM disappeared.
A new Aguirre y Aranzabal was founded by Imanol Aranzabal, who bought the rights to the name and maker's mark. Francisco Sarriugarte reappeared as Keman. A few of the other makers appear to have made post-DIARM guns, likely as one or two man shops.
But for the most part about twenty of the makers who had produced guns to every price point at which demand existed simply ceased to exist. That was the DIARM disaster.
If by "quality" you mean "works well and lasts long", the quality was quite good. But if you are using "quality" in the sense of social value (degree of ornamentation) then the answer would be, "varies as a function of price point."
Here are a couple of Sarriugarte marked DIARM guns:
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