To discriminate between Sruti and Smrti is not correct. Sruti, Smrti and the Puranas, all three belong to the same tradition. Sankara is said to be the abode of the three("Sruti-Smrti-Purananam alayam"). If the three were at variance with one another how can they exist in harmony in the same person?
Those who follow the tradition of Acarya are called "Smartas". The word "Smarta" literally means one who adheres to the Smrtis. To say that the Acarya descended to earth to uphold the Vedas and that those who follow his path are Smartas implies that the Vedas and Smrtis are one.
The rites that are not explicitly mentioned in the Vedas but are dealt with in the Smrtis are called Smarta karmas and those that are explicitly mentioned are called Srauta karmas. This does not mean that the Smarta rites are in anyway inferior to Srauta. The householder's Smarta works include such an important rite as aupasana; equally important are the domestic rites like sraddha and the seven pakayajnas. Vedic mantras are chanted in all these. Those who composed the Smrtis and laid down the performance of such rites must have been fully aware of the spirit of the Vedas. It is not proper to think that the Smrtis are inferior to the Vedas or that the Puranas are inferior to the Smrtis. We must learn to take an integrated view of all of them.
In Puranas the Vedic truths are illustrated in the form of stories. The Smrtis bring the Vedic dharmas and karmas in the form of instruction and injunctions and tell us how the rites are to be performed.
The sages had intuitive knowledge of the Vedas. As mentioned so often they did not compose them - they saw them. There was no intellectual effort on their part in this. "Srutim pasyanti munayah" (The sages see the Vedas). They used their intelligence to examine what they saw and, remembering it all, derived from the Vedas the duties and rites for various castes. This they gave us in a codified form called Smrti. As I said before "Smrti" means memory. For the sages the Vedas constituted an experience that just happened to them. The Smrtis or the dharmasastras are derived from their memory of it. "Samskara-janyam jnanam Smrtih", the Nyaya-sastra define Smrti thus. It means that Smrti is knowledge derived from Samskara. Here "Samskara" means "atindriya". But what exactly is it?
We go to Kasi and worship at the temple of Visvanatha there. Many days after our return home, we go to the local temple which has a sanctum of "Kasi Visvanatha". At once we remember the experience we had of seeing the deity Visvanatha at Kasi. In between for many days, that is between our visit to Kasi and to the local temple, we had no memory of this deity. We come across so many people every day but we hardly think of them later. But, when we happen to see them subsequently, we tell ourselves: "Ah, we must have seen them before somewhere. " In between there was no memory of the people. This "in between state" is called "samskara" or "atindriya". In that state there is an impression of our experience within us. When this impression manifests itself as an "expression" we have "Smrti" or memory. All told, Smrti is the result of our experience and samskara an impression of that experience within us.
The experience constituted by the Vedas and manifested as the memory is the Smrti or Dharmasastra. Smrti does not become Smrti without its Vedic root. Are not the Vedas the"experience" that is the source of the Smrtis? Without such a source the name suggesting "notes of memory" would be meaningless. How can we describe as notes of remembrance" anything that is new and is not founded on something prior to it?
There is no second opinion regarding the fact that what is called "Srauta"(directly mentioned in the Vedas) is wholly authoritative. But what is not directly mentioned in Sruti but included in Smrti - that is Smarta - is not to be taken to be less authoritative. Smarta never contradicts Srauta. In some matters Smritis may go beyond Sruti, but that too is fully authoritative being based on the inner spirit of Sruti. Just as the Sthala Puranas fill in the gaps in the major Puranas and the epics, so the Smrtis speak of what is left out in the Vedas. We use terms "Sruti pramana" and "Smrti pramana"(the authority of the Vedas and the authority of the Smrtis), but making such a distinction does not mean that we should treat Sruti and Smrti different or that we should think that the one is inferior to the other.
For a general background, please see here